Question

Case Study – AbdomenPresentation/HistoryA 33-year-old medical secretary comes to the physician's office complaining of nausea and vomiting of bile-stained food, with sensations of bloating, belching, discomfort, and pain in the upper abdomen. These symptoms come on approximately one to two hours after meals. Following a respiratory infection she suffered a marked weight loss amounting to twenty-five pounds during the last six months. Since then her symptoms have gradually worsened.On inquiry she states that since adolescence she has had alternating periods of well-being and abdominal discomfort accompanied by vomiting. Since the recent aggravation of her symptoms, she has felt very fatigued and has lost her appetite. She further states that when she has these attacks of pain and vomiting she can obtain relief by lying on her side or in the knee-chest position.ExaminationOn physical examination we find a rather apprehensive patient of asthenic habitus, particularly conspicuous since she shows evidence of recent marked weight loss. She has very flaccid abdominal walls and her liver, kidneys, and spleen can be palpated easily. As is common in asthenic individuals, she has a marked lumbar lordosis. The epigastrium is rather tender, but otherwise no signs of acute intestinal illness, such as rigidity of the abdominal wall or indications of intestinal obstruction, can be elicited. The patient is advised to seek admittance to the hospital for further studies.In the hospital a full-blown attack is observed, which came on after a fairly large meal with a meat course and dessert. She was stricken with nausea and fairly severe cramping pain in the right upper abdominal quadrant. She vomited bile-stained food that she had eaten recently. The vomiting relieved her pain. Before the attack subsided, the examining physician noted that the patient displayed tenderness and visible peristalsis in the right upper abdominal region.Radiographic study of the upright patient under the fluoroscope with a radiopaque meal shows rapid emptying of the stomach, which permits exclusion of pyloric stenosis. The first three portions of the duodenum fill rapidly and are considerably dilated. Under active peristalsis the duodenum finally empties part of the barium into its fourth portion, but there is marked indentation of the barium filling at the site of transition of the third and fourth lumbar vertebrae. This corresponds to the cutoff point at the time of the beginning of filling of the duodenum. X-ray examination six hours after the barium meal shows a marked and abnormal residue of barium in the duodenum.DiscussionObstruction of the third portion of the duodenum as a clinical entity is an interesting phenomenon. Enthusiasm for this diagnosis has waxed and waned since the disease was first defined in the mid-1800’s. There are still authors who deny the occurrence of such an entity, but the majority of clinicians are now convinced of its existence, particularly when confirmed by radiographic evidence. Anatomists and pathologists have known for a long time that postmortem casts of the duodenum frequently show an imprint of the superior mesenteric vessels on the anterior wall of its third part. The equivalent of this imprint has been demonstrated in vivo by radiologic means as a filling defect in the same location.1) Describe the position of the parietal peritoneum, transverse colon, mesocolon, pancreas, aorta, and superior mesenteric vessels in relation to the third part of the duodenum (9).It can be palpated to the right of the mesenteric root. This part of the duodenum, which is also often called the inferior or horizontal portion, is about three inches in length. It begins at the inferior duodenal flexure as the continuation of the descending portion and generally crosses the third lumbar vertebra. At its left extremity it becomes the fourth or ascending portion that terminates as the duodenojejunal flexure.The mesenteric vessels pass over the third part of the duodenum to enter the mesentery and to supply the small and large intestines from the distal duodenum to the left colic flexure. The superior mesenteric vein drains the same area of intestine and courses to the right of the artery. Their relationship to each other is easy to remember if one keeps in mind that the artery arises from the aorta in the midsagittal plane while the vein drains into the portal vein in its course toward the liver which is essentially a right-sided organ.

2) Trace the course of the superior mesenteric artery from the aorta as it wraps around the pancreas (4).In its course, the artery is surrounded by the superior mesenteric nerve plexus. Since the artery runs posterior to the neck of the pancreas it is, of course, also posterior to the transverse mesocolon which arises from the anterior surface of the pancreas. It is worthwhile to keep in mind that, while the origin of the superior mesenteric artery is cranial to the third portion of the duodenum, the origin of the inferior mesenteric artery is caudal to this part of the duodenum. It is also easy to remember that the superior and inferior mesenteric veins, which accompany the two mesenteric arteries both lie to the outside of the arteries, i.e. closer to the lateral abdominal wall than the arteries. Since the duodenum, with the exception of its first portion, is a retroperitoneal structure, its position is less variable than organs having a mesentery. Nevertheless, it is surprising to observe that the duodenum is relatively mobile in vivo. Its location varies with body posture being lowest in the upright and highest in the prone position. It also changes with the degree of its filling and the state of contraction of the anterior abdominal wall. It descends with age. Thus, the level of the third lumbar vertebra or of the disk caudal to it, represents only a mean as a landmark for locating the third portion of the duodenum, with the range extending from L2 to L5.3) Complete the following embryologic migration of these structures, explaining the eventual retroperitoneal position of the major part of the duodenum and the retrovascular location of the third portion of this viscus in relation to the super mesenteric vessels (9). The intestinal tube forms an__________ convex loop in the __________plane and is suspended from the wall of the abdomen by a mesentery. The tube then rapidly increases in __________ and undergoes a rotation by __________ degrees, with the superior mesenteric artery acting as the axis of __________. The superior mesenteric artery comes to lie __________ to the duodenum but __________ to the transverse colon.The cardinal point of this discussion is, of course, the pathogenesis of the clinical entity exemplified by our patient. While normally the superior mesenteric vessels pass gently over the third part of the duodenum, in our case we have to visualize the transverse duodenum as being markedly compressed, as in a vise, between the aorta and/or lordotic vertebral column posteriorly and the taut mesenteric vessels anteriorly. This happens if, due to severe weight loss in an asthenic patient with insufficient abdominal muscular support, the intestines drop caudally to an undue degree. Thus, marked traction is exerted on the superior mesenteric vessels at the site of the mesenteric root. This can lead to acute or intermittent chronic obstruction of the duodenum at this level.4) Describe what is meant by the term " asthenic habitus," so well demonstrated by this patient (1).5) Give an anatomic explanation for the symptoms of the patient in the acute stages of her illness (3). 6) Speculate as to the reason for the intermittent occurrence of her attacks with free intervals in between (2).The x-ray examination of the patient reveals, in addition to the dilatation of the duodenum proximal to the obstruction, increased peristalsis leading to emptying of the duodenum through the duodenojejunal flexure. Records of other cases also show hypertrophy of the duodenal musculature with dilation proximal to the obstruction. It is understandable that incomplete constriction can become complete with exhaustion of the propelling musculature force. We then face an acute, life-threatening clinical picture that requires immediate surgery. The recent aggravation of all symptoms in the patient is due to severe loss of weight and increased flaccidity of her abdominal musculature. The weight loss has resulted in diminution of the fat cushion in the mesenteric root that so far had protected the duodenum from complete and lasting compression. The accompanying loss of fat in the pelvis, greater omentum, and retroperitoneal structures, and the weakening of her abdominal musculature, has led to further sagging of the intestines into the pelvis and an increase of the drag on the mesenteric vessels. This further decreases the acute angle between aorta and superior mesenteric artery, a process that has been compared with the action of a nutcracker clamping down on the third part of the duodenum. Clinicians and radiologists have reported that manual pressure on the lower abdomen in a cephalic direction with the patient in the supine position will relieve the retention by lifting the intestine out of the true pelvis. Pathologists have obtained similar results at autopsy by raising the viscera after opening of the peritoneal cavity, and have observed the passage of liquid contents or air beyond the point of obstruction after this maneuver.7) Identify two additional factors that may contribute to arteriomesenteric occlusion by tightening the vise on the inferior part of the duodenum (2).

Answer 1

ANSWER :

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1)RELATIONS TO 3rd PART OF DUODENUM :

3rd part of duodenum also known as horizontal or inferior part of duodenum.

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• Parietal peritoneum : 3rd part of duodenum is retroperitoneal and fixed.
• Transverse colon , mesocolon : These are present anteriorly to the 3rd part of duodenum
• Pancreas : Head of pancreas and uncinate process are present superiorly to the 3rd part of duodenum
• Aorta : Aorta present posteriorly to the 3rd part of duodenum
• Superior mesenteric vessels : Present anterior to the 3rd part of duodenum.

3rd part of duodenum is most liable to obstruction because of its typical relations :

• It is retroperitoneal , so it is more susceptible to pressure against vertebral column.
• Duodenum lies in between the angle formed by superior mesentric artery anteriorly amd aorta posteriorly. Narrowing of this angle leads to obstruction.