Postoperative omental infarction following colonic resection.

AIM: To illustrate the computed tomography (CT) appearances and natural history of postoperative omental infarction following colonic resection and to highlight the important clinical implications of this radiological diagnosis. MATERIALS AND METHODS: Over a 3 year period, 15 patients with a history of colonic resection were identified as having a CT diagnosis of postoperative omental infarction. Relevant clinical and pathological data were retrospectively collected from the institution's electronic patient records system and all relevant imaging was reviewed, including serial CT images in 10 patients. RESULTS: A diagnosis of postoperative omental infarction was made in symptomatic and asymptomatic patients who had undergone open or laparoscopic colonic resection for benign or malignant disease. CT appearances ranged from diffuse omental stranding to discrete masses, which typically appeared within weeks of surgery and could persist for years. In four (36%) of the patients with colorectal cancer, the CT appearances raised concern for recurrent malignancy, but percutaneous biopsy and/or serial CT allowed a confident diagnosis of omental infarction to be made. Although most cases were self-limiting, three (20%) cases were complicated by secondary infection and required radiological or surgical intervention. CONCLUSION: Postoperative omental infarction is an under-recognized complication of colonic resection. It has the potential to mimic recurrent malignancy and may require radiological or surgical intervention for secondary infection.

Acute gastrointestinal haemorrhage: the role of the radiologist.

Acute gastrointestinal (GI) haemorrhage is a frequent and potentially life threatening medical presentation, the management of which depends on more than one speciality. Upper GI haemorrhage is often treated by endoscopic methods, failing which radiological intervention or surgery are the alternative methods of treatment. Radiology is crucial both in the diagnosis and treatment of lower GI haemorrhage, where the role of endoscopy is limited by poor visibility. CT angiography is now the first line investigation of choice and catheter angiography is used as a prelude to intervention. Interventional radiological techniques for treatment include embolisation for both upper and lower GI arterial haemorrhage and transjugular intrahepatic portosystemic shunting for upper GI variceal haemorrhage refractory to endoscopic treatment.

Duplex sonography in the planning and evaluation of arteriovenous fistulae for haemodialysis.

This paper describes how to perform duplex sonography in the planning and evaluation of arteriovenous fistulae in haemodialysis patients, discusses its roles in these settings, and presents a review of commonly encountered complications.

Suppression of the postoperative neutrophil leucocytosis following neoadjuvant chemoradiotherapy for rectal cancer and implications for surgical morbidity.

OBJECTIVE: The extent to which neoadjuvant chemoradiotherapy for rectal cancer influences postoperative morbidity is controversial. This study investigated whether this treatment suppresses the normal perioperative inflammatory response and explored the clinical implications. METHOD: Prospective databases were queried to identify 37 consecutive study patients undergoing definitive surgery following 5-FU/capecitabine-based chemoradiotherapy and 34 consecutive untreated control patients operated upon for rectal or rectosigmoid cancer. Preoperative (< 10 days) and postoperative (< 24 h) neutrophil counts, along with morbidity data, were confirmed retrospectively. Univariate and multivariate analyses assessed the apparent effect of chemoradiotherapy on change in neutrophil count. The latter's association with postoperative morbidity was then examined. RESULTS: Sufficient data were available for 34 study and 27 control patients. Repeated-measures ANCOVA revealed significant differences between their perioperative neutrophil counts (P = 0.02). Of the other characteristics which differed between the groups, only age and tumour location were prognostically significant regarding perioperative change in neutrophil count. Accounting for relevant covariates, chemoradiotherapy was significantly associated with a suppressed perioperative neutrophil leucocytosis. Local postoperative complications affected 25 of 61 patients, who had lower perioperative neutrophil increases than their counterparts (P = 0.016). CONCLUSION: Chemoradiotherapy appears to suppress the perioperative inflammatory response, thereby increasing susceptibility to local postoperative complications.

Delaying surgery after neoadjuvant chemoradiotherapy for rectal cancer may reduce postoperative morbidity without compromising prognosis.

BACKGROUND: This retrospective study investigated whether the interval between neoadjuvant chemoradiotherapy and surgery for rectal cancer influences postoperative morbidity or prognosis. METHODS: Data from 189 patients receiving neoadjuvant 5-fluorouracil-based chemoradiotherapy were examined. Associations between interval length and clinicopathological characteristics were analysed. RESULTS: The median interval was 73 (range 6-215) days. Operations performed were abdominoperineal resection (60.3 per cent), anterior resection (37.6 per cent) and Hartmann's procedure (2.1 per cent). Forty-six patients (24.3 per cent) received postoperative chemotherapy. Interval was not significantly associated with pathological tumour (P = 0.648) or node (P = 0.964) category after chemoradiotherapy, or pathological complete response (P = 0.499). Logistic regression showed that shorter intervals (by 1 week) independently predicted anastomotic leakage (odds ratio (OR) 0.97 (95 per cent confidence interval (c.i.) 0.94 to 1.00)) and perineal wound complications (OR 0.97 (0.95 to 0.99)). Interval was not related to local recurrence (hazard ratio (HR) 1.01 (95 per cent c.i. 1.00 to 1.02)), metastasis (HR 1.00 (0.99 to 1.01)) or death (HR 1.00 (0.99 to 1.01)). Only circumferential resection margin and nodal involvement were independent predictors of survival. CONCLUSION: Delaying surgery beyond 8 weeks after neoadjuvant chemoradiotherapy may reduce postoperative morbidity, without compromising prognosis.

Population dynamics of sand flies (diptera: psychodidae) at two foci of leishmaniasis in Texas.

Sand flies were collected at a focus of leishmaniasis in Medina County, TX, from April through October 1997 and at a focus in Bexar County, TX, from April 1998 through December 1999. Lutzomyia diabolica (Hall) were collected from April through November with peak abundance in July. The male:female ratio of Lu. diabolica was 1:6.2. Almost all female Lu. diabolica in the collections were unfed. One gravid Lu. diabolica contained 49 ova. Female Lu. anthophora (Addis) were active from February through December with three peaks in abundance suggestive of successive generations. Unfed and gravid Lu. anthophora were collected in about equal numbers. Gravid females contained from 1 to 64 ova per female. The male:female ratio was 1:1.8, with male Lu. anthophora collected in all months. One female Lu. anthophora was found infected with Leishmania in July 1999. Lutzomyia texana (Dampf) were collected from April through October with peak abundance in April during 1997. The male:female ratio was 1:1.4, with most females unfed. Two gravid Lu. texana contained 32 and 102 ova. An undescribed species of Lutzomyia was found only at the Medina County site from May through September 1997. Trapping sites four times per month versus two times per month in 1999 did not appear to adversely affect the abundance of Lu. diabolica or Lu. anthophora. There were marked differences in the species composition and relative abundance at the different sites, indicating that the spatial distribution of sand flies is patchy in nature.

Further support for a Palaearctic origin of Leishmania.

The fossil record and systematics of murid rodents, reservoirs of zoonotic cutaneous leishmaniasis in the Palaearctic, Oriental, African, Nearctic and Neotropical, strongly support a Palaearctic origin of Leishmania. The fossil record and systematics of phlebotomine sand flies reinforce this idea. Interpretations of molecular data that place the origin of Leishmania in the Neotropical are inconsistent with the natural histories of reservoirs and vectors. The evolutionary pattern of New World rats (Sigmodontinae) indicates that they may be the most important reservoirs of zoonotic cutaneous leishmaniasis throughout their range.

Palaearctic origin of Leishmania.

The hypothesis of a Palaearctic origin of Leishmania in the early Cenozoic, dispersal to the Nearctic in the late Eocene and to the Neotropical in the Pliocene is presented. It is further hypothesized that murid rodents and their immediate ancestors have been important mammalian reservoirs since the origination of Leishmania. Biochemical, molecular, biogeographical, entomological, mammalalogical and ecological support for these hypotheses are reviewed.

Short report: a focus of Leishmania mexicana near Tucson, Arizona.

Twenty-eight white-throated woodrats (Neotoma albigula) collected in Pima County, Arizona were screened for Leishmania using culture and the polymerase chain reaction (PCR). Two rodents were culture positive. Isoenzyme analysis determined the isolates to be Leishmania mexicana. The two culture-positive and four additional rodents were determined to be Leishmania-positive by the PCR. These isolates extend the geographic and ecologic range of enzootic leishmaniasis in the United States and represent a new host record.

Leishmaniasis in Texas: prevalence and seasonal transmission of Leishmania mexicana in Neotoma micropus.

The annual prevalence of Leishmania mexicana in Neotoma micropus from 16 southern Texas localities was determined by screening 192 N. micropus using in vitro culture. Eight woodrats also were screened using the polymerase chain reaction (PCR). Forty-six Sigmodon hispidus from four localities were also tested. Seasonal transmission was investigated through trap-recapture studies at three localities and analysis of infections in juveniles. Fourteen N. micropus from four localities were culture-positive for L. mexicana, indicating an annual non-zero prevalence at these localities of 5.6-27%. Four additional infections at two foci were detected only by the PCR. Transmission occurred in the fall in each case in which season of transmission could be determined. No S. hispidus were positive. These data support the hypothesis that N. micropus is a reservoir of L. mexicana in Texas.

Isolation of Leishmania mexicana from Neotoma micropus collected in Texas.

A female Neotoma micropus infected with Leishmania was collected in Zavala County, Texas, on 15 January 1990. The infection was limited to lesions at the bases of the ears, and the parasite grew readily in Schneider's Drosophila medium supplemented with 20% fetal bovine serum. Isozyme analysis determined the parasite to be Leishmania mexicana.