The Anterior Pelvic Index (API) in the Classification of the Female Pelvis and Prediction of Fetopelvic Disproportion / El Índice Pelviano Anterior (API) en la Clasificación de la Pelvis Femenina y Predicción de la Desproporción Fetopélvica

SUMMARY: Measurements of the upper strait of the pelvis can be calculated using the Anterior Pelvic Index. The objective of the study was to determine the external validity and cut-off point of the API, to classify narrow pelvises from normal ones. We selected 214 women from 15 to 55 years old, 171 had vaginal delivery and 43 by caesarean section by feto-pelvic disproportion (FPD) of maternal origin, in whom the API was calculated, of which its mean difference was established with an alpha error of <0.05. Maximum values of sensitivity and specificity, ROC curve and Youden index were determined. The student's t gave a p-value =0.000 of the mean difference between the women who had vaginal delivery and those who had cesarean section by FPD of maternal origin; the value of the area under the ROC curve was 0.758 (CI 95% 0.695 - 0.814) with a p-value=0.0001. Maximum sensitivity was 74.42 % (CI 95%: 58.8 % to 86.5 %) and maximum specificity was 73.10 % (CI 95%: 65.8 % to 79.6 %), produced a Youden index of 0.475 (CI 95% 0.283 - 0.590) which is associated with the 15.44 (CI 95% 14.19 - 15.83) of the API scale. The API is a good tool for predicting women with suspected narrow pelvis and allows its classification into three types of pelvises: an API value of more than 15.83 would indicate pelvis suitable for vaginal delivery; an API value between 14.19 and 15.83 would be suspected of pelvic narrowness; an API value less than 14.19 would confirm a narrow pelvis.

Las medidas del estrecho superior de la pelvis pueden calcularse mediante el Índice Pelviano Anterior. El objetivo del estudio fue determinar la validez externa y el punto de corte del API, para clasificar pelvis estrechas de las normales. Seleccionamos 214 mujeres de 15 a 55 años, 171 tuvieron parto vaginal y 43 mediante cesárea por DFP de origen materno, en quienes se calculó el API, del cual se estableció su diferencia de medias con un error alfa de <0,05. Se determinaron valores máximos de sensibilidad y especificidad, curva ROC e índice de Youden. La t de Student dio un p-valor=0,000 de la diferencia de medias entre las mujeres de tuvieron parto vaginal y las que fueron sometidas a cesárea por DFP de origen materno; el valor del área bajo la curva ROC fue 0,758 (IC 95% 0,695 - 0,814) con un p- valor=0,0001. La máxima sensibilidad (74,42 %. IC 95%: 58,8 % a 86,5 %) y máxima especificidad (73,10 %. IC 95%: 65,8 % a 79,6 %), produjeron un índice de Youden de 0,475 (IC 95% 0,283 - 0,590) el cual está asociado al valor 15,44 (IC 95% 14,19 - 15,83) de la escala del API. El API es una buena herramienta de predicción de mujeres con sospecha de pelvis estrecha y permite su clasificación en tres tipos de pelvis: un valor de API de mas de 15,83 indicaría pelvis aptas para un parto vaginal; un valor de API entre 14,19 y 15,83 se sospecharía de estrechez pélvica; un valor de API menor a 14,19 confirmaría una pelvis estrecha.

The sonographic measurement of the ratio between the fetal head circumference and the obstetrical conjugate is accurate in predicting the risk of labor arrest: results from a multicenter prospective study.

BACKGROUND: Labor arrest is estimated to account for approximately one-third of all primary cesarean deliveries, and is associated with an increased risk of adverse maternal and perinatal outcomes. One of the main causes is the mismatch between the size of the birth canal and that of the fetus, a condition usually referred to as cephalopelvic disproportion. OBJECTIVE: This study aimed to describe a new ultrasound predictor of labor arrest leading to cesarean delivery because of suspected cephalopelvic disproportion. STUDY DESIGN: This was a multicenter prospective study conducted at 3 maternity units from January 2021 to January 2022. A nonconsecutive series of singleton pregnancies with cephalic-presenting fetuses, gestational age of 34 weeks+0 days or above, and no contraindication to vaginal delivery attending at the antenatal clinics of each institution were considered eligible. Between 34+0 and 38+0 weeks of gestation, all eligible patients were submitted to transabdominal 2D ultrasound measurement of the obstetrical conjugate. On admission to the labor ward, the fetal head circumference was measured on the standard transthalamic plane by transabdominal ultrasound. The primary outcome of the study was the accuracy of the ratio between the fetal head circumference and the obstetrical conjugate measurement (ie, head circumference/obstetrical conjugate ratio) in predicting the occurrence of cesarean delivery secondary to labor arrest. The secondary outcome was the relationship between the head circumference/obstetrical conjugate ratio and labor duration. RESULTS: A total of 263 women were included. Cesarean delivery for labor arrest was performed in 7.6% (20/263) of the included cases and was associated with more frequent use of epidural analgesia (95.0% vs 45.7%; P<.001), longer second stage of labor (193 [120-240] vs 34.0 [13.8-66.5] minutes; P=.002), shorter obstetrical conjugate (111 [108-114] vs 121 [116-125] mm; P<.001), higher head circumference/obstetrical conjugate ratio (3.2 [3.2-3.35] vs 2.9 [2.8-3.0]; P<.001), and higher birthweight (3678 [3501-3916] vs 3352 [3095-3680] g; P=.003) compared with vaginal delivery. At logistic regression analysis, the head circumference/obstetrical conjugate ratio expressed as Z-score was the only parameter independently associated with risk of cesarean delivery for labor arrest (odds ratio, 8.8; 95% confidence interval, 3.6-21.7) and had higher accuracy in predicting cesarean delivery compared with the accuracy of fetal head circumference and obstetrical conjugate alone, with an area under the curve of 0.91 (95% confidence interval, 81.7-99.5; P<.001). A positive correlation between the head circumference/obstetrical conjugate ratio and length of the second stage of labor was found (Pearson coefficient, 0.16; P=.018). CONCLUSION: Our study, conducted on an unselected low-risk population, demonstrated that the head circumference/obstetrical conjugate ratio is a reliable antenatal predictor of labor arrest leading to cesarean delivery.

Three-dimensional magnetic resonance pelvimetry: A new technique for evaluating the female pelvis in pregnancy.

OBJECTIVE: To describe three-dimensional (3D) magnetic resonance imaging (MRI) pelvimetry methods and to establish the pelvimetric reference in a large population of Chinese females at term pregnancy. METHODS: Three-hundred one pregnant women at term who underwent MRI were included. Three-dimensional pelvic models were reconstructed using Mimics. 10.0 software based on MRI data sets, and measurements of these models were made. Pelvimetric results according to delivery modality were presented. Additionally, the previously described CT 3D pelvimetry method for predicting cephalopelvic disproportion (CPD) was used to validate its accuracy. RESULTS: Two hundred ten women underwent vaginal delivery, and 13 underwent caesarean delivery for CPD. 3D modelling of the pelvis of pregnant women was feasible using MR data sets. Pelvimetric parameters in the vaginal delivery group were as follows: transverse diameter, 134.7 mm ±â€¯7.5; obstetric conjugate, 126.9 mm ±â€¯8.3; interspinous distance, 113.4 mm ±â€¯8.2; sagittal midpelvis, 117.8 mm ±â€¯8.1; intertuberous distance, 127.1 mm ±â€¯10.4; sagittal outlet, 110.2 mm ±â€¯8.9, and posterior sagittal outlet, 59.7 mm ±â€¯8.1. According to the previously described CT 3D pelvimetry method for predicting CPD, 67.6% (142/210) of women in the vaginal delivery group were diagnosed with CPD. CONCLUSION: 3D MR pelvimetry is a novel method for determining pelvic dimensions at term pregnancy. A prospective trial is needed to establish a useful value for predicting CPD in Chinese females at high risk of CPD.

Management of osteogenesis imperfecta type I in pregnancy; a review of literature applied to clinical practice.

PURPOSE: Osteogenesis imperfecta (OI) is a rare heritable heterogenous disorder characterized by bone fragility and susceptibility to fractures with a wide spectrum of clinical expression due to defects in collagen type I biosynthesis. The purpose of the review is to highlight the practical norms in pregnancies with osteogenesis imperfecta. METHODS: We carried out a literature review in MEDLINE on OI during pregnancy, focusing on diagnosis, therapy and delivery. We reviewed 28 articles (case reports, original articles and reviews). RESULTS: Pregnant women affected by type I OI should be closely monitored to assess fetal well-being and detect pregnancy-related complications associated with an increased risk for osteoporosis, restrictive pulmonary disease, cephalopelvic disproportion and other problems related to connective tissue disorders. Mode of delivery remains controversial and should be determined on an individual basis. CONCLUSION: In conclusion, women affected by type I OI represent a subset of patients whose pregnancies should be considered high risk and warrant a multidisciplinary approach in a referral center.

Fetal pelvic index to predict cephalopelvic disproportion - a retrospective clinical cohort study.

OBJECTIVE: To investigate the diagnostic accuracy of the fetal pelvic index to predict cephalopelvic disproportion. DESIGN: Retrospective observational cohort study. SETTING: Pregnant women who had been examined by X-ray or magnetic resonance imaging pelvimetry because of an increased risk of fetal-pelvic disproportion during 2000-2008 in North Karelia Central Hospital. POPULATION: A total of 274 pregnant women. METHODS: Univariable and multivariable regression analyses were carried out to identify risk factors for cesarean section. Diagnostic accuracy was tested with a receiver operating characteristic curve, and the optimal cut-off value for fetal pelvic index was calculated. MAIN OUTCOME MEASURE: Cesarean section rates. RESULTS: A total of 242 women delivered vaginally, and 32 delivered with cesarean section caused by labor arrest. In multivariable modeling, the fetal pelvic index, maternal pelvic inlet size, fetal head circumference and maternal age were significantly associated with a risk of cesarean section. In the receiver operating characteristic analysis, the area under curve was 0.686 with a p-value of 0.001 and a 95% confidence interval of 0.595-0.778. The optimal fetal pelvic index cut-off value according to the receiver operating characteristic was -0.65. The cesarean section rate was 8% below the fetal pelvic index value of -0.65 and 20% above the fetal pelvic index value of -0.65. CONCLUSIONS: The fetal pelvic index was not a clinically useful tool to predict the mode of delivery for patients at high risk of cephalopelvic disproportion. The pooled analysis of the current and previous studies strengthened this conclusion.

The diagnostic accuracy of pelvic measurements: threshold values and fetal size.

PURPOSE: This study aimed to correlate pelvic dimensions and fetal size to the risk for cesarean section caused by protracted labor. METHODS: This is an observational, retrospective cohort study on pregnant women with an increased risk of labor dystocia. After pelvimetry, pelvic adequacy was clinically tested in a trial of labor. A multivariable regression analysis was made to identify the risk factors for cesarean section. Two subgroups were established according to the size of the estimated fetal head circumference (HC) (arbitrary cutoffs of ≤340 and >340 mm), and the pelvic measurements were compared by the mode of delivery. Receiver operating characteristic (ROC) curves were evaluated. RESULTS: Altogether, 274 patients were ultimately included. The mean size of the maternal inlet was 1.0 cm larger in fetal HC >340 mm group compared with ≤340 mm. In the vaginal delivery group, the difference was 1.3 cm. In the multivariable modeling, maternal age (odds ratio [OR] 1.09, 95 % confidence interval [CI] 1.02-1.17), fetal HC (OR 1.05, 95 % CI 1.02-1.09), and maternal inlet circumference (OR 0.95, 95 % CI 0.92-0.97) had significance for the risk of cesarean section. In the ROC analysis, the area under the curve (AUC) value for the pelvic inlet was 0.736 (p < 0.001, 95 % CI 0.656-0.816), and in the subgroups with fetal HC ≤340 and >340 mm, AUCs were 0.634 (p < 0.11, 95 % CI 0.493-0.775) and 0.836 (p < 0.001, 95 % CI 0.751-0921), respectively. CONCLUSIONS: Labor arrest was associated with the linear relationship between the maternal pelvic dimensions and the fetal size. Therefore, the approach should be changed from standardized pelvimetric threshold values to passenger-passageway ratio analyzed by multivariable modeling to find more accurate methods to predict cephalopelvic disproportion.

Adherence to guidelines on the diagnosis of cephalo-pelvic disproportion at Maharaj Nakorn Chiang Mai Hospital.

OBJECTIVE: To determine the degree of adherence to guidelines on the diagnosis of cephalopelvic disproportion (CPD) in Maharaj Nakorn Chiang Mai Hospital. MATERIAL AND METHOD: The database ofpregnant women who underwent cesarean delivery due to CPD between 2010 and 2012 was reviewed The degree of adherence to guidelines on the CPD diagnosis was recorded The guidelines were from Royal Thai College of Obstetricians and Gynecologists (RTCOG) and the American Congress of Obstetricians and Gynecologists (ACOG) as gold standard criteria for CPD diagnosis. RESULTS: Four hundred sixty four pregnant women diagnosed as CPD were recruited. The adherence to guidelines either RTCOG or ACOG criteria was 80.4%. Of 91 cases that had incomplete criteria to diagnose CPD, 25 cases (27.5%) had been suspected offetal macrosomia and CPD was diagnosed during latent phase of labor Unfortunately, 76% of these fetuses had birth weight less than 4000 grams, which were unlikely to be macrosomia. CONCLUSION: The adherence to guidelines on the diagnosis of CPD was 80.4%. Almost one-third of the cases that had no adherence were false diagnosed of fetal macrosomia. Therefore, the strategy of accurate fetal weigh estimation may reduce unnecessary cesarean section from false diagnosis of CPD.

Anthropometric measurements as predictors of cephalopelvic disproportion: Can the diagnostic accuracy be improved?

OBJECTIVE: We assessed the efficacy of maternal anthropometric measurements and clinical estimates of fetal weight in isolation and in combination as predictors of cephalopelvic disproportion (CPD). DESIGN: Prospective cohort study. SETTING: Tertiary care teaching hospital, two affiliated hospitals with facilities for conducting cesarean delivery and seven affiliated primary care facilities with no operation theaters. SAMPLE: Primigravidae over 37 weeks' gestation attending these facilities during a 20-month period with a singleton pregnancy in vertex presentation. METHODS: Several anthropometric measurements were taken in 249 primigravidae. Fetal weight was estimated. Differences in these measurements between the vaginal delivery and CPD groups were analyzed. The validity of these measurements in predicting CPD was analyzed by plotting receiver operating characteristic curves and by logistic regression analysis. MAIN OUTCOME MEASURE: Mode of delivery. RESULTS: Maternal height, foot size, inter-trochanteric diameter and bis-acromial diameter showed the highest positive predictive values for CPD. Combining some maternal measurements with estimates of fetal weight increased predictive values modestly, which are likely to be greater if the estimates of fetal weight are close to the actual birth weight. Based on multivariate analysis the risk factors for CPD in our population were foot length ≤23cm, inter-trochanteric diameter ≤30cm and estimated fetal weight ≥3 000g. CONCLUSIONS: Maternal anthropometric measurements can predict CPD to some extent. Combining maternal measurements with clinical estimates of fetal weight only enhances the predictive value to a relatively modest degree (positive predictive value 24%).

The relationship of ethnicity, maternal height and shoe size, and method of delivery.

In a bid to determine the relationship of ethnicity, maternal height and shoe size as predictors of cephalopelvic disproportion, we conducted a prospective comparative study of primigravidas at term with singleton pregnancies, who had undergone spontaneous labour. A total of 208 primigravidas were studied; 151 (62.9%) achieved vaginal delivery and 57 (37.1%) had emergency caesarean section for failure-to-progress. We found a statistically significant positive correlation between maternal height and vaginal delivery (p = 0.04), but no correlation with maternal shoe size was found (p = 0.24). This study also showed that Caucasian women were significantly more than twice as likely to achieve vaginal delivery compared with Africans (p = 0.02). Maternal height of at least 162.5 cm, has a sensitivity of 74% and a specificity of 43% for predicting vaginal delivery. We concluded that the most predictive anthropometric measurement for vaginal delivery is maternal height.

[Detection of cephalopelvic disproportion using a virtual reality model: a feasibility study of three cases]. / Détection des disproportions fœtopelviennes par réalité virtuelle : étude de faisabilité à propos de trois cas.

Routine daily practice shows that successful vaginal delivery for women with suspected narrow pelvis or large fetus remains possible. We present a computer software for the detection of fetopelvic disproportion based on 3D vectorial reconstructions of the fetal head and maternal pelvis with simulation of head passage through the pelvis for collision detection. Three delivery simulations were generated from MR pelvimetry data in two patients, one with narrow pelvis and the other with macrosomic fetus. Based on the simulation, fetus size in both cases was appropriate for the pelvic size, but delivery simulation for the macrosomic fetus concluded that vaginal delivery was mechanically impossible. Further evaluation of this promising software on a larger patient population is necessary.

[Fetal-pelvic disproportion and X-ray pelvimetry]. / Disproportion foeto-pelvienne et radiopelvimétrie.

OBJECTIVES: X-ray pelvimetry is a method that not only allows exploring the pelvic inlet but also would partially explain the "fetal-pelvic disproportion". The aims of this study are to estimate this capacity to actually explain the aforementioned disproportion, assessing as well its influence on the follow-up of later pregnancies. PATIENTS AND METHODS: A retrospective study was performed in Angers' hospital, France. We went back over 11 years and included 90 nulliparous patients, all of whom had a C-section due to "fetal-pelvic disproportion". We defined a specific sub-group for arrest of labor. RESULTS: Only 55.5% of the patients had an unfavorable Magnin's index (<23 cm) and 47.8% were, according to it, in the uncertainty - or dystocia - zone. Labor arrest was explained by mechanical obstruction (72% of the patients had pelvic abnormalities) and by dysfunctional patterns (40% due to a posterior position of the occiput, 18% because of hypotonic labor). An important number of elective C-sections (55 cases) was recorded for subsequent pregnancies. Reasons were bound to X-ray pelvimetry (35 cases), the patients' wish (two cases), to maternal pathology (four cases), to a hydramnios (three cases) and to the suspicion of fetal distress (five cases). DISCUSSION AND CONCLUSIONS: The term "fetal-pelvic disproportion" should be carefully used. Some authors used it in case of arrest of labor during two hours, a normal dynamic pattern, sufficient cervical dilation and, for many, an occipoanterior position.

Guidelines for computed tomography and magnetic resonance imaging use during pregnancy and lactation.

There has been a substantial increase in the use of computed tomography (CT) and magnetic resonance imaging (MRI) in pregnancy and lactation. Among some physicians and patients, however, there are misperceptions regarding risks, safety, and appropriate use of these modalities in pregnancy. We have developed a set of evidence-based guidelines for the use of CT, MRI, and contrast media during pregnancy for selected indications including suspected acute appendicitis, pulmonary embolism, renal colic, trauma, and cephalopelvic disproportion. Ultrasonography is the initial modality of choice for suspected appendicitis, but if the ultrasound examination is negative, MRI or CT can be obtained. Computed tomography should be the initial diagnostic imaging modality for suspected pulmonary embolism. Ultrasonography should be the initial study of choice for suspected renal colic. Ultrasonography can be the initial imaging evaluation for trauma, but CT should be performed if serious injury is suspected. Pelvimetry now is used rarely for suspected cephalopelvic disproportion, but when required, low-dose CT pelvimetry can be performed with minimal risk. Although iodinated contrast seems safe to use in pregnancy, intravenous gadolinium is contraindicated and should be used only when absolutely essential. It seems to be safe to continue breast-feeding immediately after receiving iodinated contrast or gadolinium. Although teratogenesis is not a major concern after exposure to prenatal diagnostic radiation, carcinogenesis is a potential risk. When used appropriately, CT and MRI can be valuable tools in imaging pregnant and lactating women; risks and benefits always should be considered and discussed with patients.

Development of risk scoring scheme for prediction of cesarean delivery due to cephalopelvic disproportion in Lamphun Hospital, Thailand.

AIM: To develop a simple risk scoring scheme for the prediction of cesarean delivery due to cephalopelvic disproportion (CPD) in Lamphun Hospital, Thailand. METHODS: A case-control study was conducted including 116 pregnant women with cesarean delivery due to CPD and 307 pregnant women delivering by normal labor. Obstetric information was retrieved from medical records. Risk indicators measurable at the time of admission were analyzed by a stepwise logistic regression to obtain a set of statistically significant predictors. Regression coefficients were transformed into item scores and added up to a total score. Risk of cesarean delivery due to CPD was analyzed using total scores as the only predictor. RESULTS: A risk scoring scheme was developed from five obstetric predictors: maternal age, height, parity, pregnancy weight gain and symphysis-fundal height. Item scores ranged from 0 up to 3.5 and the total score from 0-14.5. The scheme explained, by the area under the receiver operating characteristic curve, 88% of cesarean delivery due to CPD. The likelihood of cesarean delivery due to CPD in pregnant women with low risk (scores below 5), moderate risk (scores 5-9.5) and high risk (scores 10 and over) were 0.09, 0.86 and 10.11, respectively. CONCLUSIONS: The risk of cesarean delivery due to CPD may be forecasted by a simple scoring scheme using five predictors that correctly identified women with low, moderate and high risk. This scheme may be applicable to physicians and midwives for identifying high-risk pregnant women in order to take appropriate action.

Anthropometric measurements in the diagnosis of pelvic size: an analysis of maternal height and shoe size and computed tomography pelvimetric data.

BACKGROUND: To determine whether measurements of maternal height and shoe size are predictors of pelvic size, using erect lateral computerized tomography (CT) pelvimetry as gold standard. MATERIALS AND METHODS: Three hundred and fifty three obstetric patients out of a sequential population of 6112 (5.8%) had CT pelvimetry performed between January 1990 and December 1991 at the Department of Obstetrics and Gynecology, York District Hospital, United Kingdom. Multivariable logistic regression models were built using maternal height (n = 322), shoe size (314) and weight at last clinic visit (n = 318). The reference standard for pelvic size was CT Pelvimetry. Pelvic adequacy was defined as an anterior-posterior diameter of the inlet of > or =11 cm and an anterior-posterior diameter of the outlet > or =10 cm on erect lateral CT pelvimetry. Women with values lower than these were regarded as having an inadequate pelvis. The diagnostic accuracy of the models was determined by the area under the receiver operating characteristic curve (AUC). RESULTS: The area under the curve (AUC) for maternal height (0.768) was not significantly greater than that for shoe size (0.686, p = 0.163 for the difference in AUC's) and weight at the last clinic visit (0.655, p = 0.057 for the difference in the AUCs). The change in the AUC for each of the models (the full model with height, shoe size and weight [0.769]; model for height and shoe size [0.767] model for just height [0.768]) was also not significantly different. CONCLUSIONS: Measurements of maternal height, shoe size and weight at the last clinic visit are not useful for the identification of women with inadequate pelvis.

Cephalopelvic disproportion is associated with an altered uterine contraction shape in the active phase of labor.

OBJECTIVE: The purpose of this study was to determine if intrapartum contractions of a particular shape (rapid rise with slower return to baseline) are predictive of cephalopelvic disproportion (CPD). STUDY DESIGN: In an institutional review board (IRB)-approved study, cohorts of 100 women who underwent spontaneous vaginal delivery (SVD) and 100 who underwent cesarean section (C/S) for CPD or arrest of labor were consecutively identified between January 2004 and March 2005. Inclusion criteria included term, singleton pregnancies, nulliparity, and absence of fetal anomalies. One hour of interpretable electronic fetal monitoring (EFM) was obtained in active labor. Fall to rise (F:R) ratio was calculated by measuring the time for a contraction to return to its baseline from its peak ("fall") and the time for a contraction to rise to its peak ("rise"). The F:Rs were then averaged over the number of contractions. Data were analyzed using Student t test, Chi-square, and Fisher exact tests where appropriate. RESULTS: Maternal demographics are listed in Table I. The average F:R ratio was 1.55 for SVD versus 1.77 for C/S, a statistically significant difference (P = .00003). Analysis of variance revealed this difference persists when controlled for the potentially confounding factors shown. At F:R >1.76, moreover, there was a trend towards larger birth weight (P = .06). CONCLUSION: Our study demonstrates there is a difference in uterine contraction configuration that is more common in those labors destined for C/S due to CPD. This may indicate the presence of a heretofore unknown feedback mechanism as the uterus adapts to the dysfunctional labor.

[The use of forceps in a university hospital unit]. / Les applications de forceps en milieu hospitalier universitaire.

The authors report a series of 400 forceps deliveries practiced between 1 January 1968 and 30 June 1971, in a university hospital unit. Forceps were used in 3.9 percent of deliveries; 76.9 percent of cases were practiced on primaparas. The authors also note the frequency of narrow pelvis (27.2 percent of cases). The principal indication for the use of forceps is fetal distress or arrested progress (50 percent). Forceps are most often applied at the level of the vulva or in the lower third of the pelvic cavity (44 percent of cases). However, it is also noted that 9 percent of the applications were made in the middle third and that 4.6 percent of the applications were in the upper third (forceps indispensable). Thus the authors challenge the unnecessary use of forceps and note several failures (3.5 percent) that led to Caesarian sections, principally because of feto-pelvic disproportion. Maternal lesions are more frequent when the infant is large, when there is occipito-posterior or occipito-transverse presentation and when the pelvis is slightly narrowed. As regards the fetus, in 400 cases of forceps delivery there was one fetal death connected with the use of the instrument itself. Concerning the problem of persistent posterior presentation, manual rotation should always be attempted, as instrumental rotation is dangerous and should not be used in patients with a narrow pelvis. Rotation of the head towards the front is justified by the reduction in maternal lesions, although the fetal prognosis remains the same. In the face of these statistics, modern obstetrics has evolved and all difficult forceps deliveries have been rejected in favour of Caesarian delivery.