49: Bloody Stool

I. PROBLEM

A newborn infant has passed a bloody stool. This is generally a benign and self-limiting disorder. In a large majority of patients, the cause is unknown, but it is important to detect the cases that have significant underlying pathology.

II. IMMEDIATE QUESTIONS

1. Is the stool grossly bloody? Hematochezia (bright red or maroon colored stool) is usually an ominous sign; an exception is a bloody stool as a result of swallowed maternal blood, which is a benign condition. A grossly bloody stool usually signifies lower gastrointestinal (GI) bleeding (typically below the ligament of Treitz, which is the anatomic landmark of the duodenojejunal junction): it includes the jejunum, ileum, cecum, colon, rectum, and anus. Hematochezia can occur rarely with massive upper gastrointestinal tract bleeding. Necrotizing enterocolitis (NEC) is the most common cause of bloody stool in premature infants and should be strongly suspected.

2. Is the stool otherwise normal in color but with streaks of blood? What is the consistency of the stool? This is more characteristic of a lesion in the anal canal, such as anal fissure. Anal fissure is the most common cause of bleeding in well infants. A hard stool usually signifies a fissure; a loose or diarrheal stool signifies colitis.

3. Is the stool black and tarry looking? Melena (black or tarry stools) suggests blood in the stool from the upper gastrointestinal tract (proximal to the ligament of Treitz: esophagus, stomach, or duodenum). It can also be from bleeding from the small bowel or proximal ascending colon if transit is slow enough to allow bacteria to denature the hemoglobin. Nasogastric trauma and swallowed maternal blood are common causes.

4. Is it occult blood (fecal occult blood testing/hemoccult) positive only? Microscopic blood as an isolated finding is usually not significant. Tests for occult blood are very sensitive and can be positive with repeated rectal temperatures or any perianal dermatitis.

5. Was the infant given vitamin K at birth? Hemorrhagic disease of the newborn or any coagulopathy may present with bloody stools.

6. What medications are the mother and infant on? Certain medications can cause bleeding. If the mother was on thiazides, phenobarbital, oral anticoagulants, or anticonvulsants, these can cross the placenta and cause coagulation abnormalities in the infant. If the infant has been given nonsteroidal anti-inflammatory drugs, heparin, tolazoline, indomethacin, or dexamethasone, these are all associated with bleeding.

7. Is the infant well or is the infant ill? Infants with NEC, Hirschsprung enterocolitis, or volvulus are ill; infants with an anal fissure, a milk protein allergy, or nodular lymphoid hyperplasia can appear well.

III. DIFFERENTIAL DIAGNOSIS

The most common routine reasons are swallowed maternal blood and fissures. Significant hemorrhages are usually caused by a duodenal or gastric ulcer.

1. Melena (black tarry stools). Usually from the upper GI tract but can be from the small bowel or proximal colon, as noted previously.

   1. Maternal blood. Swallowing of maternal blood during delivery (melena neonatorum) accounts ...