Kasai Procedure: Everything You Need to Know

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The Kasai procedure, also known as hepatoportoenterostomy or Kasai portoenterostomy, is a surgery performed on infants in which blocked bile ducts are bypassed to restore normal bile flow. The flow of bile, a fluid produced by the liver that aids with digestion, can become obstructed when the ducts do not form properly during pregnancy.

If left untreated, the condition, called biliary atresia, can cause severe liver damage due to the backflow of bile. The Kasai procedure is considered the first-line treatment of biliary atresia.

Although it does not cure the condition, it can slow the progression of liver injury. Even so, many children who have undergone the Kasai procedure will eventually need a liver transplant, even if the surgery is considered successful.

Surgery is the only reliable means to treat biliary atresia.

Infant with jaundice in neonatal intensive care unit
Jim Champion / Flickr Creative Commons 

What Is the Kasai Procedure?

The Kasai procedure was developed in 1951 by a Japanese pediatric surgeon named Morio Kasai to treat biliary atresia, a condition that affects between 400 and 600 newborns in the United States each year.

Biliary atresia is often the result of a congenital anomaly called a choledochal cyst, which causes bile ducts to swell and become obstructed. While rare in the United States, choledochal cysts are more commonly seen in Japan, China, and other parts of East Asia.

The Kasia procedure is an inpatient surgery used in the first-line treatment of biliary atresia. It involves the removal of the damaged bile ducts and gallbladder (the pear-shaped organ that stores and releases bile), after which a segment of the child's small intestine is sewn to the liver to restore the bile flow.

The Kasai procedure can either be performed as an open surgery (involving a large incision) or a minimally invasive laparoscopic surgery (involving smaller "keyhole" incisions and specialized narrow instruments).

Laparoscopic Kasai operations are technically challenging given an infant's small body size, but are increasingly being performed by skilled pediatric surgeons.

The Kasai procedure is performed as a matter of urgency. It is not a definitive cure, but can often normalize the bile flow and minimize damage to the liver, often for decades.

Indications for Surgery

The Kasai procedure is performed upon the diagnosis of biliary atresia. There are no contraindications for treatment.

If left untreated, biliary atresia can become life-threatening within months or years, leading to liver fibrosis (scarring), cirrhosis, liver failure, and death. Current research suggests that the three-year survival rate for untreated children is less than 10%. With treatment, many children with biliary atresia can survive well into adulthood.

Potential Risks

The risks of the Kasai procedure are not unlike that of any other surgery and may include pain, postoperative infection, and an adverse reaction to the anesthesia.

With the Kasai procedure specifically, there are other potential risks, including the following.

  • Acute cholangitis: This serious infection of the biliary tract, manifesting with fever, abdominal pain, nausea, vomiting, and jaundice, can usually be treated effectively with intravenous antibiotics.
  • Portal hypertension: This postoperative complication, characterized by abnormally high blood pressure in the liver, generally affects children who already have significant liver scarring. It can lead to bloody stools, bloody vomit, and the abnormal swelling of the abdomen (ascites). Portal hypertension is usually an indication of a poor prognosis.
  • Hepatopulmonary syndrome: This surgical complication, characterized by shortness of breath, cyanosis (bluing of the skin), and finger clubbing, is caused by dilation of blood vessels in the lungs and usually affects those who have already sustained significant liver damage. Liver transplantation is likely the only viable option at this stage.

Despite being a major surgery, the postoperative mortality rate of the Kasai procedure is only around 1.5%.

Purpose of the Kasai Procedure

The Kasai procedure is performed as soon as biliary atresia is diagnosed. The surgery should not be delayed, as doing so can increase the risk of complications and treatment failure.

If performed within 60 days of birth, the Kasai procedure has a response rate of around 68%. After 90 days, the response rate drops dramatically, to often as low as 15%. However, although the age of the infant may influence the prognosis, a late diagnosis (occurring after 90 days) does not mean that the surgery is likely to fail. Children as old as 7 months have been successfully treated with the Kasai procedure.

The diagnosis of biliary atresia is not always straightforward, in part because the disorder is often indistinguishable from neonatal jaundice, a usually harmless condition that affects as many as 80% of preterm babies and 60% of full-term babies.

Doctors will often suspect biliary atresia when the following cascade of symptoms develops within two and six weeks of birth:

  • Persistent jaundice (yellowing of the skin and eyes)
  • Pale, chalky stools
  • Dark urine
  • Hepatomegaly (enlarged liver)
  • Splenomegaly (enlarged spleen)
  • Poor weight gain

Biliary atresia can be confirmed with a combination of a physical exam, liver function tests, an abdominal ultrasound, and a liver biopsy. These procedures can all be performed within a matter of days.

As with any disease, the success of the Kasai procedure depends on numerous factors, including the stage of fibrosis prior to surgery, the degree of biliary impairment, the general health of the child, and the degree of post-surgical bile flow.

How to Prepare

Being faced with any pediatric surgery can be stressful, but knowing what to expect can help ease some of the anxiety.


The Kasai procedure is performed in the operating room of a hospital. Because it is a specialized procedure, it is often performed in a dedicated children's hospital equipped with anesthesia machines, mechanical ventilators, and surgical equipment specially designed for infants, babies, and young children.

Food and Drink

The food and drink restrictions for surgery in children are not as complex as those of adults, but still need to be strictly adhered to. Fasting helps prevent the risk of pulmonary aspiration, in which food is accidentally vomited into the lungs.

Although the risk of pulmonary aspiration is low in babies (only around 0.1%), parents will still be instructed to stop the following foods in the hours leading up to the surgery:

Type When to Stop
Solid food 6 hours before surgery
Formula milk 6 hours before surgery
Breast milk 4 hours before surgery
Clear fluids 1 hour before surgery

These guidelines can further minimize the risk of pulmonary aspiration while reducing thirst, anxiety, and irritability in children awaiting surgery. Longer periods of fasting may be needed for children with diabetes, cerebral palsy, or gastroesophageal reflux disease.


There are a few medications used in infants that can pose harm if taken before surgery. In adults, for instance, nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin and Aleve (naproxen) are routinely avoided due to the risk of postoperative bleeding, but these are not used in babies.

The only exception is Advil (ibuprofen), which can be used in children over 3 months. With that said, if Advil is needed to treat fever, the surgery will likely be postponed until the cause of the fever is identified and treated.

To avoid drug interactions, advise the surgeon about any medication your child is taking, whether it is prescription or over-the-counter.

What to Bring

As the parent or guardian, you will need to bring some form of photo ID (such a driver's license) to check in at hospital admissions. You will also need to bring your insurance card or insurance documents showing that the child is on your plan or covered by government plans like the Children's Health Insurance Program (CHIP).

Because a Kasai procedure requires an extended hospital stay, be sure to bring enough of your child's medication to cover the visit, which the nurses will dispense along with any postoperative drugs.

You should also bring your child's favorite blanket, toys, or a pacifier to help comfort them. For infants, the hospital will supply all of their daily care needs, including diapers, food, and bottles.

What to Expect on the Day of Surgery

Parents are usually advised of the exact time of the surgery a day or two in advance. By doing so, the hospital scheduler will have a better idea of the day's schedule and avoid any backlogs that might lead to unnecessarily long waiting times.

After arrival, you will be asked to fill out medical history forms and sign a consent form stating that you understand the aims and risks of the surgery.

Before the Surgery

Once registration is complete, a surgical staff member will lead you and your child to a preoperative area, where a nurse will take your child's weight and height (which helps calculate the correct anesthesia dose) and vital signs (including temperature, heart rate, and blood pressure).

Your child is then prepped for surgery either in a private or semi-private room or cubicle. Because the preoperative procedures can be scary and uncomfortable for children, the nurse may provide a mild sedative to induce relaxation and prevent squirming or panic.

For the Kasai procedure, preoperative preparations will involve the following.

  • Electrocardiogram (ECG): Used to monitor heart activity, the ECG is connected to the child's torso via adhesive electrodes.
  • Pulse oximetry: Used to monitor blood oxygen saturation, the pulse oximeter is typically attached to the child's big toe with a velcro strap.
  • Intravenous line: Used to deliver anesthesia, medications, and fluids, the intravenous (IV) line is usually inserted into a vein in the foot of non-walking children. It can also be inserted into the non-dominant hand.

In some cases, a nasogastric tube may be inserted into the child's nostril and fed into a stomach to deliver food after surgery. In addition to ensuring continuous nutrition, a nasogastric tube reduces pressure on the internal wounds, hastens the return of normal bowel function, and speeds recovery.

Before surgery, you will meet with the anesthesiologist, who will ask about allergies or any adverse reaction your child may have had to anesthesia in the past. The anesthesiologist will also explain the anesthesia procedure and answer any questions you have.

Although you may or may not see the pediatric surgeon prior to the surgery, a staff member will be on hand to keep you apprised of the progress and when your child will likely be wheeled to recovery.

During the Surgery

Once the child prepped for surgery and wheeled into the surgical suite, anesthesia is delivered. Depending on whether the surgery is open or laparoscopic, the choices include the following.

  • General anesthesia: This is a type of anesthesia delivered by IV that puts the child into an unconscious state. It is used for open surgery but may also be chosen for laparoscopic surgery in children with advanced liver disease.
  • Regional anesthesia: This form of anesthesia is used to block pain signals. It may involve a peripheral nerve block (involving an injection near a bundle of nerves) or an epidural (involving an injection into the spine). Regional anesthesia is commonly supported by monitored anesthesia care, a form of IV sedation used to induce a "twilight sleep."

Once the child has been anesthetized and vital signs are stable, the surgery can begin. There are two major stages to the Kasai procedure: biliary duct resection and Roux-en-Y hepaticojejunostomy.

Biliary Duct Resection

The surgeon starts by exposing the porta hepatis, a part of the liver from which ducts and vessels enter and leave the organ. They do so by cutting away the damaged ducts and surrounding tissues right up to the liver capsule (the connective tissue surrounding the liver).

Roux-en-Y Hepaticojejunostomy

The Roux-en-Y procedure, commonly used for gastric bypass surgery, is used here to divert the flow of bile into the intestines. For this stage, the small intestine is severed just below the stomach, and the lower portion is attached to the liver capsule.

The upper portion is then looped around and reattached to the side of the lower portion so that the bile and contents of the stomach are fed into the same intestinal passageway.

Once completed, surgical drains are placed inside the incision and held in place by an anchor suture. The abdominal wound is then closed with sutures or adhesive strips and bandaged.

After the Surgery

After the surgery, your child is wheeled into the post-anesthesia recovery unit (PACU) and monitored until they awaken from the anesthesia. Admission into the intensive care unit (ICU) may be needed, although this is less common today.

Depending on the type of surgery used, you can expect your child to be hospitalized for anywhere from five to 10 days after the Kasai procedure.

For the first two to three days, your child will not eat so that the internal wounds have a better chance of healing. Nutrition will instead be delivered either through a nasogastric tube or intravenously. The child will be monitored for flatulence and bowel movements, both of which signal the return of normal intestinal function.

In addition to pain medications and antibiotics, your child may be prescribed corticosteroid drugs (a.k.a. steroids) to reduce inflammation and swelling of the liver. The treatment will typically need to be continued after discharge.

The surgical drain will be removed once the drainage stops, usually within three to five days of the surgery.


Even after your child is discharged from the hospital, it may take a while for the liver to fully heal and the bile flow to begin to normalize.

During this period, daily oral antibiotics will be prescribed to prevent cholangitis. The treatment will likely be needed for a few months. Since common infections can lead to cholangitis, frequent handwashing, routine vaccinations, and the avoidance of colds and flu is a must.

Your child will also be placed on bile acid replacement medications like Cholbam (cholic acid) that help improve bile flow. Treatment will likely be needed for several years.

Breastfeeding is typically recommended, since it provides types of fats that are easier for the liver to absorb. If you cannot breastfeed, your surgeon will recommend a special formula that may be better tolerated than regular formula.

Proper wound care is essential to ensuring a speedy recovery.

When to Call a Doctor

Call your surgeon immediately if you notice any signs of infection or liver dysfunction in the days and weeks following the surgery, including:

  • A high fever (100.4 F or over)
  • Increased redness, pain, or oozing from the wound
  • Confusion, extreme dizziness, or fainting
  • Abdominal swelling or pain
  • Unusual bruising or bleeding
  • No bowel movement for more than three days
  • Watery diarrhea for more than three days
  • Jaundice that returns or gets worse
  • Pale or white-color stools
  • Bloody stool or vomit

Follow-Up Care

Once the surgery is complete, it will take several months before you know whether the Kasai procedure actually worked. During the first month, it is not uncommon for the bile flow to remain low, then gradually increase to normal or near-normal levels within a few months.

During this time, you will need to adhere to routine follow-up with your child's gastroenterologist or hepatologist to monitor for any changes in the bile output or liver status. The follow-up evaluations mainly involve the following.

  • Blood tests: Alkaline phosphatase, gamma-glutamyltransferase, and bilirubin are three liver functions tests that can help establish whether the biliary flow is improving or not.
  • Ultrasound elastography: This special ultrasound technique, also known as a FibroScan, is used to detect and measure liver fibrosis.

If the bile flow does not improve—indicating treatment failure—liver transplantation may be the only viable option. This will typically be performed before the child's second birthday.

Possible Future Surgeries

Even if the Kasai procedure is a success, there is a fairly strong likelihood that a liver transplant will be needed in the future. According to the American Liver Foundation, only around 25% of children who undergo the Kasai procedure will survive into their 20s without needing a transplant.

There are several actors that may improve the long-term prognosis. For instance, children whose jaundice resolves within three months of the Kasai procedure have a 75% to 90% chance of surviving at least 10 years without a transplant.

By contrast, those who are treated late (after 120 days) have only a 42% chance of surviving for two years without a transplant, even if the Kasai procedure is initially successful.

The outlook for children undergoing a liver transplant is good. All told, around 90% will survive for at least five years, while 75% will survive for 15 to 20 years with good quality of life.

A Word From Verywell

As distressing as it may be to learn that your infant has biliary atresia, it is important to remember that surgical techniques have improved enormously in recent years, as has the long-term management of liver disease after surgery.

Prior to the introduction of the Kasai procedure, children with biliary atresia rarely survived beyond their third year. Today, those who have undergone the procedure have been known to survive for 30 years without a transplant.

If your baby experiences jaundice or has persistent jaundice in the weeks following delivery, do not be swayed by people who might tell you that this is "normal." While jaundice is newborns is not uncommon, it usually resolves within five days.

Persistent jaundice is an entirely different issue and needs to be checked out immediately. If biliary atresia is involved, early diagnosis and treatment almost always confer better results.

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By James Myhre & Dennis Sifris, MD
Dennis Sifris, MD, is an HIV specialist and Medical Director of LifeSense Disease Management. James Myhre is an American journalist and HIV educator.