Abstract
Pain is subjective. The level of pain a person experiences is affected not only by the painful stimulus but also by the person’s psychological interpretation of the pain and previous experiences. Medical procedures are inevitably associated with some level of discomfort but, by using analgesic and anaesthetic medications appropriately, we can minimise the pain experienced. In the outpatient setting, pain is the main driver of procedure acceptability. When appropriate techniques and equipment are used, and when analgesic use is tailored to the patient and the procedure, most women deem outpatient hysteroscopic procedures acceptable. Although performing hysteroscopic procedures under general anaesthetic means that perioperative pain is not an issue, it is still important to recognise the possibility of post-operative pain and provide adequate analgesia to manage it accordingly. The aim of this chapter is to cover techniques that can minimise pain and to discuss the use of analgesic and anaesthetic medication for hysteroscopic procedures.
6.1 Introduction
Pain is subjective. The level of pain a person experiences is affected not only by the painful stimulus but also by the person’s psychological interpretation of the pain and previous experiences. Medical procedures are inevitably associated with some level of discomfort but, by using analgesic and anaesthetic medications appropriately, we can minimise the pain experienced. In the outpatient setting, pain is the main driver of procedure acceptability. When appropriate techniques and equipment are used, and when analgesic use is tailored to the patient and the procedure, most women deem outpatient hysteroscopic procedures acceptable. Although performing hysteroscopic procedures under general anaesthetic means that perioperative pain is not an issue, it is still important to recognise the possibility of post-operative pain and provide adequate analgesia to manage it accordingly. The aim of this chapter is to cover techniques that can minimise pain and to discuss the use of analgesic and anaesthetic medication for hysteroscopic procedures. The main focus will be on managing perioperative pain during outpatient procedures in the conscious patient, but there will be some discussion regarding post-operative analgesia for inpatient procedures conducted under general anaesthesia.
6.2 Pain Sensation in the Cervix and Uterus
The cervix and uterine body have different sensory innervation. Uterine pain is usually triggered by distension, which leads to uterine cramping.
The afferent nerve fibres, which conduct pain from the cervix, travel through the uterovaginal and inferior hypogastric plexuses and the pelvic splanchnic nerves before reaching the spinal ganglia of S2–S4. The cervix also has parasympathetic innervation, and irritation of these nerves can cause the patient to experience a vasovagal episode, where the blood pressure falls and the heart slows, resulting in the patient feeling faint or losing consciousness. Pain from the uterine body and fundus is detected by nerves that travel through the uterovaginal, inferior and superior hypogastric and the intermesenteric plexuses before passing through the lumbar splanchnic nerves to reach cell bodies in the lower thoracic (T8–T10) and upper lumbar (L1) spine [1] (see Figure 2.8b).
6.3 Procedural Aspects
These aspects are discussed more fully in Chapter 5, but it is appropriate to emphasise them again here. During outpatient hysteroscopy, the approach to the procedure taken by the clinician will affect how much pain a patient experiences. Under general anaesthesia, patients do not experience pain during the procedure, so clinicians may not pay as much attention to minimising trauma to the tissues as they might with a conscious patient. This demonstrates the importance of a clinician realising that their inpatient technique does not translate to the outpatient setting. Care must be taken to minimise any unnecessary handling of tissues, even down to ensuring that the hysteroscope travels smoothly along the cervical canal. This can only be done when the operator appreciates how the angle of the lens affects the way they need to visualise their progress on screen. Ensuring that the patient is comfortable during the procedure and that painful sensations are minimised will maximise the tolerability of outpatient hysteroscopy. Being attentive to patients’ needs and performing a careful examination in a timely manner will allow most diagnostic outpatient hysteroscopies to be performed without any analgesia or anaesthesia.
Under general anaesthetic, inappropriate moving and positioning of the patient can lead to joint and nerve injuries. For example, hyperflexion of the hips in lithotomy can cause damage to the femoral, lateral cutaneous and sciatic nerves, resulting in pain, paraesthesia and impaired motor function [2]. There is also a risk of brachial plexus injury from undue pressure on the humerus or ulnar while moving and positioning the patient, or if the patient’s arm inadvertently falls from an armboard [2]. To minimise injury, patients should be placed in the proper lithotomy position, which dictates that the hip and knee are only moderately flexed with minimal abduction and external rotation of the hip joints [2]. The stirrups should be padded and placed at an equal height, and excessive movement around the hip joints should be minimised to prevent nerve stretch injuries. The arms should be pronated and padded to prevent pressure on the radial and ulnar nerves where they wind around the humerus, and arm boards should be at an angle of 90° or less to avoid hyperabduction [2].
6.4 Cervical Priming
Clinical trials have evaluated the effect of the prostaglandin misoprostol on pain scores during ambulatory hysteroscopy. Misoprostol can be given orally or vaginally to soften and dilate the cervix, making it easier to traverse the cervical canal with the hysteroscope and therefore causing less pain. However, there is no evidence to support the routine use of cervical priming with prostaglandins to reduce pain during diagnostic ambulatory hysteroscopy [3], and misoprostol has unpleasant side effects such as fever, abdominal cramping, diarrhoea and vaginal bleeding, so its use is not currently recommended. In post-menopausal women, there is increasing evidence that it neither reduces pain nor eases passage of the hysteroscope [4, 5]. However, it may be beneficial in pre-menopausal, nulliparous women, easing dilatation [4] and reducing pain during introduction of the hysteroscope [5, 6]. Further studies are required to fully evaluate which patients are most likely to benefit from cervical priming, not only for pain but also to aid dilatation for procedures requiring larger diameter instruments, such as endometrial ablation.
6.5 Analgesia
6.5.1 Outpatient Hysteroscopy
The type of analgesia needed by patients in the outpatient hysteroscopy clinic will depend on what procedure they are having. Diagnostic hysteroscopy requires very little, if any, analgesia, while more invasive, operative procedures require stronger formulations.
A Cochrane review found insufficient evidence for any benefit of non-steroidal anti-inflammatories or opioids over placebo for pain relief during diagnostic hysteroscopy, and no benefit of either of these classes of drug 30 minutes after the procedure [7]. Individual, small studies have shown that giving intravenous or intramuscular tramadol reduces the pain of outpatient hysteroscopy [8, 9], but parenteral administration an hour before the procedure is not compatible with an ambulatory service. Compared to placebo, mefenamic acid significantly reduced post-operative pain at 30 and 60 minutes after, but not during, diagnostic hysteroscopy [10]. Other studies have found no benefit from NSAIDs [11, 12]. Opiates are associated with significant side effects [13], which may cause high rates of patient dissatisfaction, so it is important to consider whether the benefit of pain relief outweighs the side effects of medication.
A recent randomised study has examined the benefit of pre-operative analgesics for reducing intraoperative pain during outpatient hysteroscopy [14]. The women were randomised to receive either 1 g of paracetamol and 600 mg of ibuprofen orally one hour prior to the procedure, or no medication. Approximately 25% of women in each arm had a diagnostic hysteroscopy only, while approximately 40% in each arm had polypectomy and a further 20% had an endometrial biopsy. Pain scores were lower and there were fewer abandoned procedures in the medicated group, although neither of these reached statistical significance. However, there were significantly fewer non-pain side effects (nausea, vomiting, hypotension) in the medicated group [14], highlighting possible additional benefits beyond pain relief. Neither the patients nor the clinicians in this study were blinded, however, which is likely to have biased these results.
Despite the lack of good-quality evidence, many hysteroscopy clinics will advise their patients to take some simple analgesia before their appointment with the aim of minimising the level of pain experienced during and after the procedure. This advice is in keeping with the recommendations made by the RCOG’s Green-top Guideline on best practice in outpatient hysteroscopy [15] and although the benefit may be unsubstantiated, the potential for risk is minimal and some patients may benefit.
Operative hysteroscopy procedures – including polypectomy, myomectomy, endometrial ablation and tubal cannulation procedures such as hysteroscopic sterilisation and selective salpinography – are more likely to necessitate analgesia as they are more invasive and take longer to perform than diagnostic procedures. Furthermore, these procedures require the use of continuous flow, operative hysteroscopy systems, with usual diameters of 4.5–6.25 mm, so dilatation of the cervix under local anaesthesia is more likely to be needed in order to access the uterine cavity (see Section 6.5.3). The practicality and timing of administering analgesics should be considered. Procedures that will permanently affect future fertility such as endometrial ablation and hysteroscopic sterilisation should not be performed as ‘see-and-treat’ procedures, as the patients need time to consider the long-term implications. This means that such procedures can be scheduled for a later date, which also provides an opportunity for pharmacological pre-medication to be given according to local protocols in advance of the operative procedure.
A Cochrane review identified two studies that investigated pain relief for outpatient hysteroscopic sterilisation. Two randomised controlled studies were identified, one of which looked at local anaesthesia and a second that compared oral oxycodone 5 mg and naproxen sodium 500 mg with intravenous sedation [16]. Patients were given either placebo tablets or placebo intravenous solution to ensure they were unaware of which treatment they had been allocated. No significant difference in total pain score was found between the two groups [16], suggesting that oral analgesia is adequate.
Endometrial ablation can be successfully performed in the outpatient setting using a variety of techniques [17–19]. The authors of the only review that aimed to evaluate analgesic regimens for endometrial ablation were unable to identify any randomised controlled trials. However, they did evaluate analgesia regimens from observational studies and noted that most studies used an NSAID, given either orally or rectally, combined with a local anaesthetic cervical block [20]. Table 6.1 lists the commonly used analgesics. The drugs can be combined to maximise the analgesic effect, taking care not to mix drugs inappropriately and considering the patient’s drug history and any allergies or intolerances. The doses in the table are the maximum daily doses but, when using the drugs as pre-medications or as rescue analgesia, a single dose may be sufficient.
Table 6.1 Analgesics commonly used for outpatient hysteroscopic procedures and after general anaesthesia
| Drug | Doses and administration | Cautions and common side effects |
|---|---|---|
| Paracetamol | 1 g every 4–6 hours to a maximum of 4 g daily PO/PR/IV | Contraindications: allergy; hepatic impairment; increase dose interval to 6 hours in renal impairment |
| Side effects: rare |
| Opioid analgesics | ||
| Codeine | 30–60 mg every 4 hours to a maximum of 240 mg daily PO/IM | Contraindications: allergy; avoid or reduce dose in hepatic and renal impairment |
| Tramadol | 50–100 mg every 4 hours to a maximum of 400 mg daily PO/IM/IV | Side effects: nausea and vomiting, constipation, dry mouth, biliary spasm; larger doses produce muscle rigidity, hypotension, respiratory depression |
| 1–2 tablets every 4–6 hours to a maximum of 8 tablets daily | |
| For all preparations the dose is 1–2 tablets every 4–6 hours to a maximum of 8 tablets daily | |
| Non-steroidal anti-inflammatory drugs | ||
| Ibuprofen | 300–400 mg 3–4 times daily, increased if necessary to a maximum of 2.4 g daily PO | Contraindications: allergy; coagulation defects; severe heart failure; avoid in patients with asthma or hepatic/renal impairment; diclofenac is contraindicated in ischaemic heart disease, cerebrovascular disease, peripheral arterial disease and mild to severe heart failure |
| Diclofenac | 75–150 mg daily in 2–3 divided doses PR/PO | Side effects: nausea, diarrhoea, gastrointestinal ulceration |
| Mefenamic acid | 500 mg 3 times daily PO | |
PO, orally; IM, intramuscularly; IV, intravenously; PR, rectally.
*Do not give paracetamol in addition to these compound preparations.
6.5.2 After General Anaesthesia
Following procedures performed under general anaesthesia, patients are often prescribed post-operative analgesia (Table 6.1). Although in many cases this is not necessary, endometrial ablation and levonorgestrel intrauterine system insertion can cause crampy abdominal pain that may persist for hours after the patient has recovered from their general anaesthesia.
6.5.3 Local Anaesthesia
Obstetrics and gynaecology trainees become accustomed to using local anaesthetics early in their training in the context of perineal repair. However, complications associated with local anaesthetic use, especially toxicity, can be life-threatening. Adrenaline is added to many local anaesthetic agents with the aim of causing vasoconstriction, which reduces blood flow. This, in turn, reduces bleeding and dispersion of the anaesthetic agent, and so provides a longer acting block. However, adrenaline is associated with cardiac complications. An alternative vasoconstrictor is felypressin, a synthetic form of vasopressin. Felypressin does not affect cardiac rate or rhythm and is a useful alternative to adrenaline. To reduce the risk of complications, doctors need to be aware of the maximum dose of local anaesthetic for each patient (based upon their weight) and should be able to recognise the signs and symptoms of systemic toxicity (Table 6.2). The maximum plasma concentration of the anaesthetic agent occurs within 25 minutes, so patients should be observed for signs of toxicity for 30 minutes after administration [21]. Considering whether vasoconstriction is really necessary for the procedure is an additional way of reducing risk. For example, during colposcopy, reducing blood flow to the area of the cervix to be excised reduces blood loss. However, for hysteroscopy, the cervix is usually dilated and not incised, so blood loss is not such a concern. If vasoconstriction is desired, then using a preparation that contains felypressin (e.g. Citanest®) may be preferable.
| Central nervous system | Cardiovascular |
|---|---|
|
|
When using local anaesthetics in an outpatient setting, rapid onset and protracted duration of action are desirable. The anaesthetics most commonly used are amides with an intermediate duration of action: lidocaine, prilocaine and mepivicaine (Table 6.3). Doses may need to be adjusted to the patient’s body mass index (BMI) and co-morbidities.
| Anaesthetic agent (generic name, trade name) | Dose* | Duration of onset | Duration of action |
|---|---|---|---|
| Lidocaine hydrochloride | 3 mg/kg up to a maximum of 200 mg [21] | <2 min [22] | 30–60 min [22] |
| Available as: | |||
| 0.5% (5 mg/ml) | |||
| 1% (10 mg/ml) | |||
| 2% (20 mg/ml)[21] | |||
| Lidocaine hydrochloride with adrenaline | 7 mg/kg up to a maximum of 500 mg [21] | <2 min [22] | 2–6 h [22] |
| Xylocaine | |||
| Lidocaine hydrochloride 1% (10 mg/ml) + adrenaline 1 in 200 000 (5 μg/ml) | |||
| or | |||
| lidocaine hydrochloride 2% (20 mg/ml) + adrenaline 1 in 200 000 (5 μg/ml) [21] | |||
| Mepivacaine | Maximum dose per procedure 400 mg [22] | 3–5 min [22] | 45–90 min [22] |
| Scandonest plain 3% | |||
| Mepivacaine hydrochloride 3% (30 mg/ml) [21] | |||
| Prilocaine hydrochloride with felypressin | 1–5 ml (30–150 mg prilocaine hydrochloride) up to a maximum of 10 ml (300 mg) [23] | 2–3 min [23] | 45 min [23] |
| Citanest 3% with Octapressin | |||
| Prilocaine hydrochloride 3% (30 mg/ml + felypressin 0.03 IU/ml) [21] |
*In obese patients, dose should be calculated based upon the patient’s ideal weight rather than their actual weight.
Related posts:
Chapter 2 – Anatomy and Physiology of the Uterus
Chapter 3 – Infrastructure and Instrumentation for Hysteroscopy
Chapter 8 – Hysteroscopic Electrosurgery
Chapter 10 – Hysteroscopic Endometrial Polypectomy
Chapter 17 – Audit, Data Collection and Clinical Governance in Hysteroscopy
Chapter 18 – Training in Hysteroscopic Skills
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