The pelvic floor is a complex anatomical unit grouping muscles, connective tissues, and bones. The pelvic muscular diaphragm is composed of the coccygeus muscle posteriorly and the levator ani anterolaterally. The levator ani consists of the iliococcygeus, the pubococcygeus, and the puborectalis muscle group. Through these structures pass the urological, genital, and intestinal tracts. The pelvic floor supports the pelvic organs and the spine. It is a complex functional unit involved in continence and evacuation of urine and stool, sexual function, and childbirth. However, the pelvic floor muscles are also part of a much wider muscular system known as the abdominal core, and act together with the diaphragm, the lower back, and the abdominal wall muscles influencing spinal stability, body posture, and breathing. The pelvic floor muscles connect with some of the muscles of the thigh and as such are activated during walking, running, and other dynamic activities. The complex functions of the pelvic floor, which are both voluntary and reflexive, include visceral and somatic activities; they are explained by their innervation through the co-activation of the somatic and the autonomic nervous system. The pelvic innervation , controlled by the supraspinal centers, explains the connections between the various pelvic organs and between these organs and their muscular links. Therefore, the pelvic floor muscles are part of a complex adaptive system, which is under the control of brain centers. The role of the pelvic muscles is related to the function of the pelvic organs and of the core abdominal muscles and as such, the pelvic muscles represent a link between the inner and the outer world. The consequence of this complexity is that their function may be altered by any of the components of this complex system.

Weakness or relaxation of the pelvic floor results in disorders such as urinary or fecal incontinence and pelvic organ prolapse, which are easily recognized. Overactive pelvic floor is more challenging to diagnose as symptom presentation may be varied and are frequently not attributed to the pelvic floor muscles. Descent of the pelvic floor organs to the perineum isn’t typically observed in overactive pelvic floor. The symptoms of an overactive pelvic floor are often nonspecific and are frequently related to abdominal organ dysfunction or to muscle pain, which presents as a dull and diffuse sensation. Defecation disorders, voiding and/or sexual dysfunction and pain are the main expressions of an overactive pelvic floor. These symptoms do not always point clearly to the involvement of the pelvic floor muscles.

In this paragraph, we will not describe the entire spectrum of the pelvic floor’s functions. Rather, we will restrict the scope to pelvic floor function as it relates to digestion and abdominal and pelvic pain. In recent literature, pelvic floor dysfunction is referred to by various terms. Several terms relate to the pathophysiology of the condition such as short pelvic floor [1], myofascial pelvic pain [2], non-relaxing pelvic floor [3], and hypertonic pelvic floor [4]. Other terms relate to the anatomical aspects of the dysfunction such as levator ani syndrome, puborectalis syndrome, piriformis syndrome, coccygodynia, although the pain was not always located in the coccyx [5]. Some more generalized terms, such as idiopathic perineal pain, are also used. This diverse terminology shows differing pathophysiological understanding for the same condition.

Defecation is a complex integrative function that involves the digestive tract, the anorectum, and the pelvic floor. The foregut is innervated by the vagal system, the hindgut by the sacral parasympathetic nerves, the levator ani by sacral nerves, the internal anal sphincter by nerves originating from L4 level, and the external anal sphincter by the pudendal nerve. Only the latter is volitional. Therefore, synchronization of the autonomic and somatic neural functions of the pelvic floor muscles is essential in order to allow normal defecation and bladder evacuation.

An overactive pelvic floor may inhibit activity in the lower rectum and reduce the urge to defecate or create a sensation of incomplete defecation [6, 7]. If the patient strains and employs Valsalva breathing in order to defecate, the over activation of the abdominal wall muscle will co-stimulate the pelvic floor muscles and impede defecation [8, 9].

The integration of pelvic floor functions is learned during childhood. To understand the complaints of a patient who suffers from pelvic floor dysfunction, we must investigate the acquisition of the various pelvic floor functions along a three-dimensional system. Those three dimensions are composed of the horizontal axis (pelvic floor structures), the vertical axis (the interaction with the central nervous system), and finally the axis of time. The central nervous system and brain axis are of particular importance as they link the inner and external world. Symptoms of pelvic floor dysfunction or pain generally occur after a long period of imbalance induced by either poor posture, a lack of synchronization between the viscera and the muscles, local persistent injuries, or stress. Each component of this complex circuitry may affect pelvic floor function.

Defecation disorders are a common cause of overactive pelvic floor and may be acquired in early childhood. Toilet training is the beginning of the cognitive control of continence. If the need to defecate is not properly perceived, recognized, or accepted, then continence may be affected. Children may learn to use a withholding mechanism and abstain from defecation, leading to inappropriate activation of the neuronal circuitry linking the rectal nerves to the sacral plexus, the spine and the brain, resulting in future abnormal behavior. Approximately 50 % of constipated children contract rather than relax the external anal sphincter during defecation [10]. This retentive habit may progress to encopresis . Eventually, this mechanical barrage will affect other anorectal functions. In one study, it was demonstrated that 95 % of children with idiopathic constipation have impaired rectal sensation and weakening of rectal contraction during distension. This mechanism contributes to diminished rectal evacuation [11]. One-third of children with idiopathic constipation who were followed up beyond puberty continued to report severe complaints of constipation [12]. Over time, this dysfunction may become painful. About half of children with acute abdominal pain suffer from constipation, which was considered to be the cause of the pain [13]. Prolonged contraction of muscles activate locally the free ends of afferent nerves fibers of the group III (thin myelinated fibers) and group IV (non-myelinated fibers), which transmit pain.

Constipated children frequently complain about urinary dysfunction such as urinary tract infection (UTI) in 11 % of the cases and urinary incontinence in 63 % of the cases. The association of urinary dysfunction with constipation is supported by the observation that resolution of fecal retention leads to the disappearance of daytime urinary incontinence in 89 % of the cases and of UTI in 100 % of the children [14].

There is a significant association between early sexual abuse and gastroenterological functional symptoms [15]. In a study published in 1995, patients with a history of sexual abuse were more likely to complain of both constipation and diarrhea. Anismus , a condition characterized by anal muscle contraction, was more frequent in sexual abuse survivors, suggesting a perturbation of pelvic floor function [16]. In other studies on sexually abused children, gastrointestinal disorders met the diagnostic criteria for somatization disorder, presenting with hypervigilance, anxiety, and psychiatric disorders. These patients have poor quality of life due to health-related issues, utilize the health care system more often, and report more pain [17].

Visceral insults may express themselves as musculoskeletal pain . Visceral pain is difficult to diagnose when it is not related to obvious inflammation, tumor, or to structural abnormalities. Visceral pain typically is not felt in the organ in which it is generated but in a distant muscular or cutaneous area of reference. This phenomenon is related to the dermatome organization of the nervous system [18]. Organ dysfunction and pain without sign of organic disease are by far more frequent [19].

These syndromes have in common a state of visceral hypersensitivity with a lower threshold of pain. Peripheral nociceptors are more responsive than normal to painful stimuli (allodynia and hyperalgesia) and this leads to central sensitization at the level of the dorsal horn. The phenomenon of viscerovisceral and visceromuscular sensitization appears and a “wind up” mechanism stimulates the brain centers and the autonomic system. The descending pain pathway becomes disinhibited and a state of chronic pain takes place.

In the periphery, the pelvic floor muscles shorten, weaken, and become a source of pain. The pain is myofascial, dull, and diffuse and is characterized by the presence of trigger points. Trigger points are sensitive spots found in tense muscles. Administering pressure to these trigger points produces pain and evokes projected pain in regional muscles. Locally, palpation of these muscles may induce a muscular twitch reaction. Initially, the muscles are thick and overactive. When the cause persists, muscles remain chronically tight, blood flow is decreased and local hypoxemia leading to reduced muscle energy is observed. This process increases muscle pain. Eventually, local muscular shortening will give rise to taut bands and tender points resulting from hypersensitivity of the neural pathway in the muscles. This hypersensitivity is due to sensitization of muscle nociceptor group III and IV afferent fibers, leading to central nervous sensitization in the spinal cord and brain. The patient may also struggle with a state of hypervigilance and stress according to the patient’s personality or experiences. If muscle contraction is maintained, a vicious cycle may take place. When this state turns chronic, the muscles will become fibrotic and weak.

The causative factors at the origin of this dysfunction may be related to pelvic viscera or to the perineal muscles. The “cross talk” between pelvic organs and the pelvic muscular layers can enhance further dysfunction and pain. Many patients have more than one underlying cause for their pain.

During chronic irritation , a negative interaction between the organ and muscles may occur. Evacuation disorders may or may not be accompanied by pain. A persistent contraction of the levator ani muscle may complicate organ dysfunction further. Persistent levator ani contraction can be the result of skeletal imbalance, poor learned defecation habits, a chronic visceral injury such as the neuroinflammation seen in irritable bowel syndrome (IBS) or interstitial cystitis, or a guarding reflex. This situation may be clinically confusing since dermatomal referred pain may last years after the primary injury is treated [20].

The dominant or initial symptoms of overactive pelvic floor may be triggered either by visceral injury or myofascial pain. The pain may or may not be associated with GI symptoms. When GI complaints do occur, typical complaints are: The patient can experience constipation with obstructive defecation , a sensation of incomplete rectal evacuation or anal blockage and a change of behavior with excessive straining to defecate and/or rectal digitation. These unpleasant sensations will sometimes induce changes in behavior such as the need to use rectal digitation, recurrent defecation attempts, or vaginal splinting in case of rectocele. Constipation may be associated with pain during or after rectal evacuation, caused by tension of the hypertonic pelvic muscles. Pain may be also related to IBS and to rectal hypersensitivity [21, 22]; however, its origin is often unclear. It is vague, dull, persistent, and enhanced by muscle activation. It is defined as a sensation of deep perineal pressure often described as a “tennis ball stuck in the rectum.” The pain may be related to dyssynergic defecation and excessive abdominal strain. In certain cases, the patient describes a cramping pain.

Pain is often more frequent during the second part of the day, absent at night and aggravated by prolonged sitting. It is often erroneously considered as pain of rectal origin although it is mainly of muscular origin. This is maintained by the Rome III classification of functional anorectal and pelvic pain, which is primarily symptom based. It divides these pains into two categories:

These categories are defined based on duration. Chronic proctalgia lasts more than 20 min. The symptoms must be present for 3 months or more in the last 6 months preceding the diagnosis. All organic causes of rectal pain must be ruled out. Chronic proctalgia is subdivided into two diagnoses:

Anorectal functional pain is mainly associated with muscular pain at the level of the puborectalis. Pain originating at the rectum, typically caused by mechanical rectal distension, is felt mainly in the lower left abdomen although it also projects to the S3 dermatome and musculotome as well. Chronic visceral pain is referred and felt in the corresponding dermatome through mechanisms of visceromuscular convergence at the sacral posterior dorsal horn level. The innervation of the rectum and levator ani originates from the sacral plexus S2–S4. This may explain why a tense levator ani and rectal pain may share the same clinical expression. Therefore, pain in these dermatomes can be purely of muscular origin but may be also caused by any of the pelvic organs sharing the same sacral innervation. Pelvic pain may be generated by other pelvic organs such as:

The link between rectal pain and the pelvic organs is through viscerosomatic convergence, as previously described.

Pain can be also evoked by other pathologies which should be excluded by a thorough examination such as:

Pain is a subjective experience triggered by peripheral causes. Symptoms are the result of integration of visceral disease, overactive muscles, and the cross talk between organs and muscles under the control of the central nervous system. It is influenced by the cognitive and emotional status of the patient. It is essential to examine the whole pelvic floor including pelvic organs and to assess for neuromuscular involvement before deciding on the best course of treatment.

There is no well-established standard for clinical assessment of pelvic floor function. Since pain may be generated by any pelvic structure or referred to the pelvic floor, the examination has to address all possible origins. Inspection of the perianal area will exclude any periorificial pathology or itching lesions. Overactive pelvic floor should be assessed by inspection of the perineum while the patient contracts the perineum as if trying to stop micturition and then relaxes. A normal reaction of the perineum would be to be lifted up and then return to the resting position. If the patient cannot relax the pelvic floor muscles upon demand or during a push down effort, a non-relaxing perineum is diagnosed. Some patients will even contract the pelvic floor while bearing down, thus demonstrating a complete inversion of the muscular command, known as dyssynergy.

Digital anal examination is performed in order to assess relaxation or contraction of the perineal muscles. Pain or tenderness of the puborectalis is evaluated by exerting mild pressure with the index finger on both sides of the posterior puborectalis sling. If the patient is reluctant to undergo anal digitation, perineal contraction assessment can be carried out through a single finger insertion in the distal vagina when the patient is lying in the left lateral position. In case of symptoms of obstructive defecation without pain, local examination may be sufficient. In case the pain is associated with other visceral signs, the examination should assess the whole pelvic floor. Other superficial and deep pelvic muscles should be palpated to determine their tonus and map the presence of taut bands and trigger points (from posterior to anterior successively the coccygeus, piriformis, internal obturator, pubococcygeus, iliococcygeus, superficial transverse perineal, perineal body, bulbospongiosus, and ischiocavernosus muscles). The coccyx, the ischial spine, and the pubis should also be palpated to assess for tenderness. When pain is the dominant symptom, a global evaluation of the pelvic floor, the gluteal muscle, lower abdomen, and lower back are also important, since pain may be associated with muscle contractions or be of referred origin. This pain-mapping is of paramount importance for establishing the correct diagnosis and plan treatment accordingly.