From the Guidelines
For a 4th degree laceration, polyethylene glycol (MiraLAX) 17g daily mixed in water is the best initial approach as it gently draws water into the stool without causing forceful contractions, thereby minimizing the risk of disrupting the healing tissues 1. When managing a 4th degree laceration, it is crucial to prioritize the prevention of constipation and straining to avoid disrupting the repair and delaying healing of the severe perineal injury.
- The use of polyethylene glycol (PEG)-3350, an osmotic laxative, is supported by indirect evidence of its benefit in patients with chronic idiopathic constipation, which presents similarly to opioid-induced constipation (OIC) in terms of clinical symptoms 1.
- Stimulant laxatives like bisacodyl or senna should be avoided as they can cause strong bowel contractions that may stress the healing tissues.
- Fiber supplements such as psyllium (Metamucil) can be added gradually once initial healing has occurred, but the primary focus should be on gentle and effective laxation to prevent constipation.
- Adequate hydration (at least 8 glasses of water daily) and a diet rich in fruits and vegetables will support the use of polyethylene glycol (MiraLAX) in maintaining regular, soft bowel movements during the critical 2-3 week healing period. The goal of this approach is to minimize pressure on the repaired tissues while promoting regular bowel movements, thereby optimizing the outcome in terms of morbidity, mortality, and quality of life for the patient recovering from a 4th degree laceration.
From the Research
Laxative Options for 4th Degree Laceration
There are no direct studies on the best laxative for 4th degree laceration. However, some studies provide information on the management of constipation and the risk of recurrence of obstetric anal sphincter injuries.
Risk of Recurrence
- A prior third-degree or fourth-degree perineal tear is associated with a 3.4-fold increased risk of a recurrent severe obstetrical laceration 2.
- The incidence of recurrent obstetric anal sphincter injuries was similar to that of primary obstetric anal sphincter injuries, and most patients went on to deliver vaginally for subsequent deliveries 3.
- The risk of recurrent obstetric anal sphincter injuries was doubled in those who delivered a large-for-gestational-age neonate and in those who had an instrumental delivery 3.
Laxative Effectiveness
- Docusate did not show any benefits for constipation when compared with placebo or psyllium or sennosides in trials 4.
- Psyllium and sennosides were found to be more effective compared with docusate for constipation 4.
- There is a lack of data to support the use of docusate for constipation, and it is not effective for use in constipation 4.