Black Stool After Surgery: Causes and Concerns

Postoperative black stools?

Hello Doctor, I underwent traditional hemorrhoid surgery on September 28, and it has been 12 days since then.
I have been taking a laxative called Lacto for constipation, 20ml once a day, but my stools have been consistently dark.
On October 4, I had a follow-up appointment, and the doctor mentioned that I might have a gastrointestinal bleed and prescribed magnesium oxide to be taken after meals and sennoside to be taken at bedtime, but there has been no change in the color of my stools; they remain dark and difficult to pass.

1.
The dark stools have persisted since my discharge; could this indicate a wound infection?
2.
How much Lacto laxative can I safely take within 24 hours? Can I take it in conjunction with the newly prescribed stool softeners? I have another follow-up appointment on October 4, or should I go to the emergency department first? Thank you for your response.

Kai Ge, 60~69 year old female. Ask Date: 2023/10/08

Dr. Zhang Shuhao reply Surgery

1.
If there is black stool without obvious bright red blood, it is likely caused by upper gastrointestinal bleeding, with the most common reason being bleeding from a gastric ulcer due to the use of nonsteroidal anti-inflammatory drugs (NSAIDs).
In this case, taking magnesium oxide (MgO) alone is ineffective; proton pump inhibitors should be used, and an upper endoscopy is necessary.
Severe bleeding may even require hospitalization for treatment.

2.
If Lacto (probiotic) is taken and there are daily bowel movements, there is no need to continue taking it.
However, if the black stool persists and is accompanied by symptoms such as dizziness, palpitations, upper abdominal pain, nausea, vomiting, or inability to eat, it is essential to go directly to the emergency department.

Reply Date: 2023/10/08

More Info

After undergoing surgery, particularly for conditions like hemorrhoids, it is not uncommon to experience changes in bowel movements, including the presence of black stools. Black stools can be concerning, as they may indicate the presence of blood that has been digested, often referred to as "melena." This can occur due to various reasons, and it is essential to understand the potential causes and when to seek further medical attention.

1. Causes of Black Stools:
- Dietary Factors: Certain foods, such as black licorice, blueberries, or iron supplements, can cause stools to appear black. If you have recently changed your diet or started taking supplements, this could be a contributing factor.

- Medications: Medications like Pepto-Bismol (bismuth subsalicylate) can also lead to black stools. If you are taking any new medications, it’s worth considering their side effects.

- Gastrointestinal Bleeding: The most concerning cause of black stools is gastrointestinal bleeding, particularly from the upper GI tract (esophagus, stomach, or duodenum). Given your recent surgery and the symptoms you described, this is a possibility that should not be overlooked.

2. Infection and Complications:
- While black stools can indicate bleeding, they do not necessarily mean that there is an infection at the surgical site. However, if you are experiencing other symptoms such as fever, increased pain, or swelling, it would be prudent to consult your healthcare provider to rule out any complications such as an infection or abscess.

3. Laxative Use:
- You mentioned taking a laxative (Lactulose) and magnesium oxide. It is crucial to follow the recommended dosage on the medication packaging or as prescribed by your doctor. Overuse of laxatives can lead to dehydration or electrolyte imbalances, which can complicate your recovery. Generally, Lactulose can be taken daily, but the exact amount should be confirmed with your healthcare provider, especially considering your current symptoms.

4. Next Steps:
- Since you have a follow-up appointment scheduled for October 4, it is advisable to discuss your symptoms with your doctor during this visit. If your black stools persist or if you develop additional symptoms such as severe abdominal pain, dizziness, or fainting, you should seek immediate medical attention, potentially at an emergency department.
5. Monitoring Symptoms:
- Keep a close eye on your bowel movements and any other symptoms you may experience. Documenting when the black stools occur, their consistency, and any accompanying symptoms can provide valuable information to your healthcare provider.

In summary, while black stools can be a benign issue related to diet or medication, given your recent surgery and the potential for gastrointestinal bleeding, it is essential to take this symptom seriously. Regular communication with your healthcare provider and timely follow-up appointments are crucial in ensuring a safe and effective recovery. If you have any doubts or if your condition worsens, do not hesitate to seek immediate medical care.

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