Duodenum Inversum

Abstract

Duodenum inversum is a rare congenital anomaly of the intestinal tract in which the normal curve of the duodenum is reversed so that the third portion, instead of turning to the left, crossing the midline and forming the duodenojejunal junction, turns to the right and takes an upward course, curving then to the left and crossing the midline above the pancreas. The designation is not applicable to the left-sided duodenum of situs inversus. Duodenum inversum is of relatively rare occurrence, although reports are appearing in the literature with increasing frequency. Addison (1) reported the discovery of 1 case in 100 consecutive anatomical dissections. Feldman and Morrison (16) found 14 instances in 20,000 gastro-intestinal x-ray examinations, an incidence of 0.07 per cent. Weinbren and McGregor (44), in 1934, reviewed the literature and estimated that the cases recorded up to that time numbered about 30. This included 11 of their own, 10 reported by Sandera (35), 5 by Hürthle (24), and several single cases. In the same year, Breton (9) and Bernay (5) each reported a case. Feldman and Morrison added their 14 cases, mentioned above, in 1940, and in the same year Fallon (15) described an example discovered in the course of an anatomical dissection. Töndury (39) recorded 5 cases in 1941. The most recent example which we found in the literature is that of von Bonin (41) in 1944. The purpose of this paper is to present 2 additional cases, bringing the total to approximately 55.2 Duodenum inversum is believed to be due to persistence of the dorsal mesentery with a mobile duodenum, and is often accompanied by anomalies in fixation or position of the right kidney, pancreas, and transverse mesocolon. Good discussions of the embryological aspects are found in the articles by Weinbren and McGregor, Feldman and Morrison, and Fallon. The reported cases show a predominance of males, about 3 or 4 to 1 female. The anomaly may be found at any age, the average being about forty-six. The range in 24 reported cases was from twenty-six to seventy years. Symptomatology Duodenum inversum is frequently asymptomatic. The commonest symptom is epigastric pain or discomfort; nausea, belching, gaseous distention, and dyspeptic symptoms are frequently encountered. Jaundice and diarrhea are often present concomitantly. Loss of weight, “bilious” attacks, anorexia, and migraine headaches may occur. Pancreatitis, gallbladder disease, duodenal ulcer, and, less commonly, gastric ulcer may be associated. Many of the symptoms are thought to be due to stasis in the duodenal loop. The diagnosis is commonly made by x-ray examination. The condition may be encountered, however, during surgery or at autopsy. Symptoms are usually relieved by conservative treatment, including rest, diet, and other methods commonly used in gastroenterologic practice. Radiologic Aspects Duodenum inversum is rarely suspected clinically.