Fig. 12.1
EAUS of postpartum EAS lesion
On the other hand, many patients with significant defect at ultrasound may be clinically asymptomatic.
Afro-Caribbean women have a lower incidence of severe trauma at delivery than white European or Hispanic. Conversely, Asian women have an increased risk, which might be related to their relatively shorter stature [38]. Again, both obesity and high birthweight seem to increase the risk of perineal trauma [39, 40]. Furthermore, in women with a history of intermittent episodes of fecal incontinence after first delivery, there is an increased risk of overt fecal incontinence after subsequent delivery. In fact, in women with sphincter injury, the risk of further severe lesions is seven times greater compared to women with healthy muscles [36].
A persistent occipito-posterior position of fetal head is associated with higher risk of third- to fourth-degree anal sphincter injury. Instrument-assisted delivery, episiotomy, and conversion to caesarean section are often required in such cases. With occipito-posterior position, sphincter laceration occurs in 42 % of patients undergoing assisted deliveries with suction cup and in 52 % of those with forceps [36].
Likewise, the prolongation of the second stage of labor is associated with an increased risk operative vaginal delivery and anal sphincter injuries, with one-third of women who have a second stage of labor more than 4 h sustaining a third- or fourth-degree injury. Women encouraged to push immediately after full cervical dilatation have an increased risk of perineal trauma compared to those where pushing is delayed. Traditionally, it is taught that applying pressure against the perineum and the descent of the baby’s head during delivery reduce the incidence of perineal injury. According to other studies, using the “hand-poised” method of childbirth whereby the accoucheur avoids touching the perineum and verbally guides the parturient, with occasional gentle support of the head, severe anal sphincter injuries and the need of episiotomy seem to be reduced, although these findings failed to reach significance [41, 42].
The risk of fecal incontinence following a non-extended midline episiotomy is three times higher when compared with spontaneous laceration. Injuries are more significant in cases of midline than those of mediolateral episiotomies.
Forceps-assisted delivery is associated with symptoms of fecal incontinence in more than 59 % of women with an incidence varying from 13 to 83 % in different studies. The risk seems to increase with occipito-posterior presentation.
Vacuum extraction compared with forceps delivery is associated with a lower incidence of clinically significant anal and perineal trauma. Delivery by caesarean section appears to play a protective role against anal sphincter injury when carried out as elective procedure or in the early stage of labor. Conversely, pelvic floor does not seem to be fully protected by caesarean section, and abdominal delivery should be considered in women at risk of further trauma after precedent vaginal delivery resulting in anatomical defects, as well as in women with symptoms of fecal incontinence after previous vaginal birth [36, 43–47].
Diagnostic Aspects
Clinical Examination
The presence of pelvic floor or even perineal skin trauma should raise suspicion for injury to sphincters, immediately after childbirth.
For example, the presence of a large vaginal laceration after childbirth may be associated with acute LAM injuries [48]. A chronic detachment of LAM from the inferior ramus of the pubic bone can be diagnosed by vaginal examination. With the patient in lithotomy position, a finger is inserted 4 cm laterally and parallel to the urethra, with the fingertip at the level of the bladder neck. The puborectal muscle insertion to the pubic bone can be palpated lateral to the index finger about 2 cm proximal to the introitus and the pubococcygeus of a young women, and according to Laycock [17], it is felt like a 1- to 2-cm firm band. Hence a chronic detachment of LAM from the inferior ramus of the pubic bone is diagnosed when moving the finger laterally, whereby the inferior ramus appears free of muscle [4].
A rectal examination is necessary before any type of instrument assessment: low anal sphincter resting tone associated with a low pressure during the contraction raises the suspicion of anal sphincter injuries. It must be considered that significant injury of one or both sphincters may be evident in the absence of LAM injuries.
Imaging
Transanal bidimensional ultrasound is still the fastest method to study anal canal anatomy, although evaluating childbirth-related trauma provides discordant results according to the timing of investigation. An EAS or IAS is simple to recognize with endoanal ultrasound, a hyperechoic (EAS) or hypoechoic (IAS) ring.
As demonstrated by Santoro et al. with endovaginal ultrasound, it is possible to achieve good visualization of the LAM described as a hyperechoic sling lying posterior to the anorectum and attaching to the pubic bone, which resembles a “gothic arch” [4]; moreover with endovaginal ultrasound, LAM injuries can be diagnosed, with good to very good interobserver and interdisciplinary reliability [49, 50].
MRI is a second-line investigation that can be performed after an ultrasound assessment, if an ultrasound examination is inconclusive.
Functional Investigations
Functional tests remain useful after imaging evaluation to obtain clinically relevant information. The first, simple, and fast examination that must be performed is anorectal manometry that can measure resting and squeeze pressures and also anal canal length. Resting pressure is impaired if an IAS defect is present; a reduction of squeeze pressure is typical finding of EAS injury.
The use of an intrarectal balloon can also evaluate the rectal compliance, sensitivity, and the rectoanal inhibitory reflex.
Altered rectal sensitivity or anal incontinence is usually transient after childbirth, with anorectal manometry showing a reduction in both resting and squeezing pressure immediately after delivery; but clinical evidence is generally poor and when significant tends to spontaneously heal. It seems that this condition is due to traction pudendal neuropathy postpartum; but clinical symptoms usually recover in about 2 months in 60 % of women. Anal incontinence may persist when weakness of pelvic floor coexists, but not all studies confirm this [51–55].
Another functional test is the pudendal nerve terminal motor latency testing (PNTML) that assesses the pudendal nerve function: although normal latencies do not exclude nerve damage, this examination is important before sphincter repair surgery because a prolonged value is a prognostic indicator of poor long-term functional success after surgery [56].
Finally there is no correlation between altered PNTML examination and presence of a sphincter defect [57].
Treatment
Pharmacological treatments are employed substantially in order to solidify the stool and prolong the intestinal transit. Constipating agents are indicated in most cases of postpartum women suffering from passive incontinence (leakage) or urgency with the intent of reducing the fecal mass and the frequency of bowel emptying. Reductions in episodes of fecal incontinence, fecal urgency, and loose stools have actually been demonstrated. Associated to clinical improvement, in patients treated with constipating agents, a reduction in weight and fecal content has been achieved. Loperamide is the most commonly used agent due to its minimal side effects and because of its greater efficacy compared to codeine and difenoxin associated with atropine. Agents promoting evacuation such as osmotic laxatives or glycerine suppositories can be adopted in cases of post-defecatory leakage or when overflow incontinence is present, often due to the presence of fecal impaction in chronically constipated individuals.
Rehabilitative therapy in the form of pelvic floor muscle training (PFMT) involves training on the right use of the pelvic floor muscles during contracting and straining, breathing, and changes in abdominal pressure, based on the use of electrostimulation and/or biofeedback. Biofeedback consists of exercises to strengthen anal sphincter and pelvic floor muscles, by improving rectal sensation and voluntary contraction of the EAS. Pelvic floor physiotherapy associated with changes in lifestyle is effective in treating patients suffering from fecal incontinence of different causes. In a study conducted by Norton and Kamm on 100 patients, it was demonstrated that a lesion of EAS alone does not seem to affect the efficacy of treatment with biofeedback, while a lesion of the IAS appears to decrease the effectiveness of the treatment. In a subsequent randomized controlled trial on 171 women conducted by Norton, in both patients with intact sphincter muscles and those with sphincter disruption, including women with childbirth trauma, effectiveness rate was comparable. However, there seems to be a direct relationship between the extent of the defect in the EAS and the effectiveness of the treatment [68, 69].
Normally only patients suffering from severe anal incontinence, in whom conservative treatment failed, require surgery. Anal sphincter injury repair can be performed at the time of childbirth or later. Delayed surgery is performed by colorectal surgeons. EAS repair may have a short-term effectiveness in up to 54 % of patients, but symptoms can worsen over time. Indeed at 3-month follow-up, a residual muscle defect at ultrasound is still detectable in more of 90 % of patients and between 30 and 61 % of patients present with fecal incontinence. Although at the short term sphincter repair seems to improve symptoms, with increased resting and squeezing manometric pressures, symptoms seem to deteriorate progressively. In fact, 10 years after surgery, only 20 % of patients remain continent to liquids and solids [36].
Other surgical procedures, such as graciloplasty, the implantation of an artificial anal sphincter (AAS), or prosthetic trans-obturator sling (TOT) (Fig. 12.2), are far more invasive and generally not recommended due to frequency and number of complications and low success rates [58, 59].
Fig. 12.2
(a) Anal sling: elastic structure that surrounds anorectal canal bilaterally fastened to obturator foramen. (b) Anal sling: the device patented in Italy, not on the market, includes the device and the hammock instruments to implant the prosthesis formed by a central body in biological material and four ends in nonabsorbable material to “suspend” the rectum and reposition it in the anatomical position
Sacral nerve stimulation (SNS) and tibial nerve stimulation (TNS) improved stool continence in several studies. SNS consists of a direct electrical stimulation to sacral plexus by means of an inplanted electrode. TNS (Fig. 12.3) provides electrical stimulation with a needle electrode (percutaneous tibial nerve stimulation) or from two pad electrodes (transcutaneous tibial nerve stimulation) both inserted into the lower, inner aspect of the leg, slightly cephalad to the medial malleolus aiming to transmit stimulation through the tibial nerve to the sacral plexus. Both SNS and PTNS showed low rate of complications and morbidity. PTNS treatment has shown an efficacy in the short term of up to 83 % [60] and in the long term, 53 %, reported by La Portilla after 2 years without treatment [61]. While for TTNS there are no studies with long-term outcomes, in the short term the efficacy is up to 60 %; in patients treated with bilateral TTNS, the efficacy is 85 % [62, 63].
Fig. 12.3
PTNS device (Uroplasty®)
In a meta-analysis that examined 34 studies published between 2000 and 2008 and included 790 patients, of whom 665 received a SNS permanent implant, SNS is an effective treatment for patients with FI compared to conservative treatment. In a multicenter, prospective nonrandomized trial that evaluated SNS in patients with FI, 83 % of 106 patients had a 50 % improvement and 40 % became fully continent, maintaining the improvement for 3 years [64, 65].
According to Wexner et al, the presence of an IAS defect, compared with its absence, is statistically associated with a lower likelihood of SNS treatment success [65].
According to Tan et al, the most common complications related with permanent SNS implantation are pain o local disconfort (6%), infection (3%) or seroma (3%),lead displacement or breakag (4%) [64].
Use of perianally injected bulking agents (BA) is a minimally invasive method for treating fecal incontinence, especially useful in those patients with higher risk of comorbidity in whom an open surgical procedure should be avoided, such as postpartum females. The procedure involves injecting prosthetic or autologous fillers into the submucosal tissues of the anorectum increase their volume and coaptation, thus preventing from incontinence episodes. Numerous studies have reported favorable short-term results with injectable perianal bulking agents, but according to Guerra et al. in the long-term follow-up, bulking agents seem to lose effectiveness and the ultrasound assessment of bulking agents suggests they are absorbed almost completely with time and the implants are no longer effective in treating incontinence [66, 67].
References
1.
Fisk NM. Caesarean section for all patients? In: Ben-Rafael Z, Lobo R, Shoham Z, editors. Controversies in obstetrics, gynaecology and infertility. Bologna: Monduzzi Editore; 2002.
2.
3.
4.
5.
Gregory WT, Nygaard I. Childbirth and pelvic floor disorders. Clin Obstet Gynecol. 2004;47(2):394–403.CrossRefPubMed
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
