Malrotation and Volvulus
Malrotation is an abnormal arrangement or twisting of the intestine inside the abdomen, which is also known as volvulus, that may result in loss of blood flow to the intestine. This abnormal arrangement or twisting of the intestine can also cause blockages of the intestines by causing a kinking of the intestine without loss of blood flow. A delay in recognizing these conditions can result in damage to the intestine as well as danger to the life of the child. To better understand why the intestine is abnormally arranged we need to understand how the stomach and intestine develop while the baby is in the womb.
Figure 1:The first part of the small intestine and the first part of the large intestine lie close together and are unattached. So, that part of the intestine can twist (black dotted line) cutting off the blood going to the entire small intestine and the first part of the large intestine. If that happens, all of that portion of the intestine may die.
At about 1 month after the baby is conceived, the developing intestine, also called the midgut, is a short, straight, continuous tube attached to the blood vessel supplying the intestine. During the first 3 months after conception the intestines must twist or rotate ¾ of a turn in order to be in the correct placement and to get the intestines to properly stick to or fix to the back of the abdomen. Rotation of the loops of the intestinal tube and lengthening of the intestine begin at about 1 month after conception. Fixation of the intestine to the inside of the abdomen occurs at the same time. If rotation and fixation does not take place, the intestine remains suspended by the thin stalk of the blood supply to the intestine and is susceptible to twisting around this stalk, also called volvulus (Figure 1).
ACUTE MIDGUT VOLVULUS
Normally the bowel is fixed to the inside of the belly or abdomen,
preventing the bowel from twisting on itself. If the bowel is not
securely fixed inside the abdomen, the intestine is suspended by a
narrow stalk that contains its entire blood supply. A twisting of the
intestine around this stalk causes the blood to stop flowing to the
intestine, which can cause bowel damage or death.
Most children who present with acute volvulus of the intestines are babies less than a year old; one-third of these babies are less than one week old, and more than half are less than one month old. The most common symptom is vomiting which is seen in more than 9 out of 10 children. The child’s vomiting may be clear at first, but eventually becomes green colored or contains bile. When the intestine gets damaged because of lack of blood flow the vomit becomes bloody. The stools are also bloody in a third of these children; one-half have a swollen belly. Stomach pains, especially when pressing the belly, are common when there is intestinal damage. Babies commonly appear sick with difficulty breathing when the intestine is damaged. However, until the intestine is damaged they may appear fairly well.
X-rays may suggest a bowel blockage. In about one-fifth of children, two bubbles of air may be seen on x-ray which may suggest a blockage of the initial part of the intestine attached to the stomach, which is called the duodenum. These x-ray results, along with blood in the vomit and stool and abdominal tenderness, suggest that an emergency operation is necessary. A special x-ray study with dye called an upper GI may be used to confirm the diagnosis.
When the diagnosis of volvulus is made in your child, preoperative preparations for the operation should be made quickly because bowel damage can develop. Antibiotics are administered. The stomach is emptied by a tube. Fluids are given rapidly through a vein to treat any dehydration.
A cut is made above the belly button so that the entire intestine can be taken out of the belly. The large intestine is not immediately seen but is found tightly encircling the base of the small bowel as part of the twist or volvulus (Figure 2). One to three complete turns are necessary to untwist the volvulus. The operation also involves dividing any tissue trying to pull the first part of the intestine to the right side of the abdomen (Figure 3) and separating the first portions of the small and large intestines so that the stalk containing the blood supply of the intestine cannot twist. (Figures 4 and 5).
Because of the abnormal position of the appendix in the left upper abdomen most surgeons remove the appendix. If damaged bowel is found your child’s surgeon may remove some of it or may decide to leave it inside and come back to look at it at a second operation. Your surgeon will try and save as much intestine as he can when he finds injured bowel and this may take multiple operations. If the operation is not done in time and all the intestine is damaged and cannot be saved the child may not be able to survive. Another serious and often fatal complication may be the result of not having enough bowel or short-gut syndrome.
Figure 3: Incising Ladd’s bands which are trying to pull the first part of the large intestine to the right side of the abdomen and which may be pressing on and blocking the first portion of the small intestine.
Figure 4: The duodenum now lies to the right and the large intestine to the left. The anterior surface of the tissue next to the intestinal blood vessels (mesentery) must be cut (dotted line) to broaden the space between the first portions of the small and large intestines so that they cannot twist.
Figure 5: The surface of the mesentery is now open and first portions of the small and large intestines are moved farther apart. Final check of proper orientation of the bowel is now done. The loops of small bowel are fanned out. The left hand in this picture encircles the first part of the small intestine, and the right hand encircles the last part of the small intestine. The remainder of the small bowel is below the hands to form an irregular U.
Malrotation in the Older Child
Malrotation can be a problem beyond the newborn period and into adulthood. Most older children have chronic symptoms and can develop a twist of their intestine causing damage to the intestine as in the newborn. In children older than age one month, one-third may vomit off and on, usually green colored with bile in the vomit, and one-fifth may have stomach aches. The most common symptoms are because of intermittent partial intestinal obstruction. Almost half of these children have poor nutrition or are underweight. In these children if x-rays show malrotation, most children’s surgeons would recommend surgery because the surgery often will make them better, and will lower the chances of intestinal damage from twisting later in life.
The need for treatment for a malrotation that is not causing any
problems for the child but is found accidentally on an x-ray study or at
operation for an unrelated reason is not clear. Some surgeons advise
that the abnormality should be corrected only in patients younger than
two years old. Others follow a more aggressive approach, stating that
the complications associated with intestinal malrotation are based on
anatomic reasons that do not change with age. They reason that volvulus
can occur at any age so that a rotational abnormality should be
corrected when it is discovered. Some surgeons do not operate on
patients with asymptomatic malrotation.
Congenital blockage of the initial part of the intestine attached to the stomach, also called the duodenum, may be associated with malrotation in newborns. If your child’s surgeon performs an operation for intestinal blockage because of malrotation they may occasionally open the stomach to look for these additional blockages.
In some children the intestine may be arranged in a normal fashion but it may not be fixed to the back of the abdomen normally. This lack of fixation of intestine may result in areas that are like pouches. Entrapment of the bowel in these pouches can lead to complete blockage and damage to the intestine from lack of blood flow. These pouches may sometimes be found on special x-ray studies or they may be found at an operation for an intestinal blockage. They can usually be treated at the time of the surgery by a children’s surgical specialist (pediatric surgeon).
Malrotation and Other Associated Conditions
Malrotation is found frequently in association with other congenital abnormalities. A form of malrotation called nonrotation almost always accompanies congenital diaphragmatic hernia and congenital defects of the abdominal wall (gastroschisis, omphalocele). Surgeons may or may not perform a corrective operation when dealing with nonrotation in these children, unless there are signs of blockage of the intestine. Malrotation also has been reported in association with other childhood diseases including congenital heart disease.
Article and graphics adapted from O'Neill: Principles of Pediatric Surgery. © 2003, Elsevier.