Malrotation with Volvulus (Midgut Volvulus)

How malrotation happens

During the first trimester, the developing intestine grows outside the abdomen, then returns and rotates 270 degrees counterclockwise before fixing in place. Normally:

• the small bowel's root (mesentery) is broad and anchored diagonally
• the cecum (start of the large bowel) settles in the lower right abdomen

In malrotation, the rotation is incomplete. The cecum ends up high and to the left of center, and the mesentery has a narrow base. Bands of tissue (Ladd's bands) may cross and compress the duodenum. The narrow base allows the whole midgut to twist around the superior mesenteric artery: a midgut volvulus.

Why it is an emergency

When the bowel twists:

1. the bowel is blocked, so bile-stained fluid backs up and is vomited
2. blood flow is cut off, and the intestine starts to die within hours
3. if not reversed, much of the small bowel can be lost, leading to short bowel syndrome, or death

The baby may look surprisingly well at first.

Symptoms

In newborns and infants

• sudden green or yellow-green vomiting (bilious vomiting): the hallmark sign
• poor feeding, irritability or drawing up the legs
• later: a swollen, tender belly, blood in the stool, pale or mottled skin, lethargy and shock

In older children and adults

Malrotation may cause:

• recurrent episodes of abdominal pain and vomiting
• feeding problems and poor weight gain
• chronic diarrhea or malabsorption
• acute volvulus at any age

Some people with malrotation never have symptoms and it is found incidentally.

Associated conditions

Malrotation is more common with congenital diaphragmatic hernia, gastroschisis, omphalocele, heterotaxy syndrome and some heart defects.

Green vomit vs other infant vomiting

Green vomit in a baby should always be treated as a surgical emergency until proven otherwise. See vomiting in infants.

Diagnosis

• upper GI contrast study: the baby swallows or is given contrast through a tube; X-rays show the abnormal position of the duodenum and a "corkscrew" pattern with volvulus. It is the standard test.
• ultrasound: can show a "whirlpool sign" of twisted vessels and an abnormal relationship of the mesenteric artery and vein
• abdominal X-ray: may be normal early or show obstruction
• blood tests: check for dehydration, acid levels and infection

If a baby is very unwell and volvulus is likely, surgeons may operate immediately without waiting for imaging.

Treatment

Before surgery

• nothing by mouth
• a tube through the nose to empty the stomach
• IV fluids and antibiotics

Ladd procedure

The surgeon:

1. untwists the bowel counterclockwise
2. divides Ladd's bands
3. widens the base of the mesentery
4. places the small bowel on the right and the large bowel on the left
5. usually removes the appendix, since it will be in an unusual position later

Dead bowel is removed. If viability is uncertain, a second-look operation is done 24 to 48 hours later. The procedure can be done open or, in selected cases, laparoscopically.

Outlook

When volvulus is treated before the bowel dies, babies usually recover fully. The risk of recurrent volvulus after a Ladd procedure is low. If large amounts of bowel are lost, short bowel syndrome may require long-term nutritional support, IV nutrition and specialized intestinal rehabilitation. Adhesive bowel obstruction can occur later in life.

Frequently asked questions

What does green vomit in a baby mean?

Green or yellow-green vomit (bilious vomiting) means bile is coming up from below the stomach, suggesting a blockage in the intestine. In a baby it can signal malrotation with volvulus, which is a surgical emergency. Go to the ER immediately.

What is malrotation with volvulus?

It is a birth defect in which the intestines are not positioned and anchored normally, allowing them to twist around their blood supply. The twist blocks the bowel and cuts off blood flow, which can kill the intestine within hours without surgery.

How is midgut volvulus diagnosed?

Usually with an emergency upper GI contrast study, which shows the abnormal position of the intestine and the twist. Ultrasound can also show the twisted blood vessels. Very ill babies may go straight to surgery.

What is the Ladd procedure?

The Ladd procedure is surgery that untwists the intestine, cuts the abnormal bands of tissue, widens the base of the bowel's attachment, places the bowel in a safer position, and usually removes the appendix. It greatly reduces the risk of future volvulus.

Can adults have intestinal malrotation?

Yes. Some people are unaware of malrotation until adulthood, when it causes chronic abdominal pain, vomiting or an acute volvulus, or is found on a scan. See intestinal malrotation for more.