Postoperative pain after total abdominal hysterectomy and bilateral salpingo-oophorectomy depending on the type of anaesthesia administration

ABSTRACT

Total abdominal hysterectomy and bilateral salpingo-oophorectomy is a surgical procedure frequently associated with severe or moderate postoperative pain. We conducted a retrospective study on 90 patients who underwent this procedure. One part of the patients (58; 64.4%) was administered bupivacaine 5% without intrathecal opioid administration. The other part (32; 35.6%) underwent general anaesthesia with endotracheal intubation. We evaluated the postoperative analgesic requirements based on the type of anaesthesia used and other factors like age, environment and body mass index. The findings indicated that the patients who received general anaesthesia with endotracheal intubation developed severe postoperative pain more frequently than those who underwent spinal anaesthesia (P = 0.018). A higher percentage of patients from rural areas scored lower in postoperative pain intensity on the numerical rating scale (P = 0.033). There was no statistically significant correlation regarding postoperative pain and age or body mass index.

KEYWORDS:

• Total abdominal hysterectomy
• postoperative pain
• spinal anaesthesia
• general anaesthesia

Introduction

Uterine fibroid (leiomyoma) is a benign tumour of the uterine smooth muscle. It is a dystrophic lesion and not an oncological tumour. There are two surgical procedures available: a more conservative one – myomectomy and a radical one – total or subtotal hysterectomy.[1]

Total abdominal hysterectomy and bilateral salpingo-oophorectomy is the procedure in which the doctor removes the uterus, including the cervix, both ovaries and fallopian tubes. The fast recovery depends on minimizing the postoperative symptoms, especially pain.[2]

This type of surgery can be performed under either general or spinal anaesthesia. Therefore, in this study, we aimed to verify whether the postoperative pain experienced by women under general anaesthesia is different from the postoperative pain experienced by women who were administered spinal anaesthesia with intrathecal bupivacaine.

Presently, there are no studies comparing the efficiency of general anaesthesia with spinal anaesthesia without opioid intrathecal administration in terms of postoperative analgesia. Intrathecal opioids were used in all of them.[3–5]

Another aspect in focus in the present paper is whether the place of origin (environment), age or body mass index (BMI) may or may not influence the postoperative pain intensity after this type of surgery.

Subjects and methods

Subjects

This study included 90 patients who underwent total hysterectomy with bilateral salpingo-oophorectomy under spinal or general anaesthesia. All procedures were performed at the same medical centre. Although the surgical team may have been different from one patient to another, we have to emphasize the fact that the key points of the surgical procedure were identical in all cases. Thus, all surgeons performed hysterectomy by using the extrafascial technique and avoided anchoring of the round ligaments to the vaginal cuff or cervical stump and peritonealization of the pelvis.

We did not include patients who received partial care in other medical centres in the present study, in an attempt to standardize the factors that could possibly affect the outcome.

All anaesthesia was performed by the sameanesthesiologist.

Study design

The study was an observational one and had received an agreement of the Ethics Committee of the Faculty of Medicine and Pharmacy, ‘Lower Danube’ University of Galati. Also, it respected the criteria of medical and deontological ethics and the law of Romania.

Medical charts were retrospectively reviewed for patients' sex, environment of origin, age and BMI.

The number of patients who underwent general anaesthesia with endotracheal intubation was 32 (35.6%). The other 58 patients (64.4%) administered spinal anaesthesia. Only 5% bupivacaine was used for the spinal anaesthesia. For the patients with general anaesthesia, induction with propofol (2 mg/kgc), fentanyl (3 μg/kg), succinylcholine (1 mg/kgc) maintained with fentanyl (2 μg/kg) and atracurium (0.1 mg/kg), and recovery with pentazocine, atropine and neostigmine, were performed, all in accordance with indication of ‘Miller's Anesthesia’ 2014.[6]

The age of the patients ranged from 33 to 60 years. Patients were divided into two groups, depending on the age criterion: the first group was composed of patients aged less than or equal to 50 years (68 patients) and the second group was composed of patients aged over 50 years (22 patients).

Another parameter we considered worth taking into consideration was the BMI. Patients were divided into five groups according to the BMI value: normal weight (BMI = 18.5–24.9 kg/m²), overweight (BMI = 25 –29.9 kg/m²), obese class I (BMI = 30–34.9 kg/m²), obese class II (BMI = 35–39.9 kg/m²) and obese class III (BMI > 40 kg/m²).

The patients were also divided into rural areas inhabitants (31 patients) and urban areas inhabitants (59 patients), depending on where they come from.

Analgesia

For assessing the level of postoperative pain, we used the numerical rating scale (NRS) by asking each patient to rate their pain.

Each patient was prompted to either verbally indicate her level of pain on a scale from 0 to 10, or to mark this level on a horizontal line. Zero indicated absence of pain, whereas 10 represented the most intense pain possible. By using the NRS, we rated the pain as: mild (1–3), moderate (4–6) and severe (7–10), and formed three groups of patients, based on these criteria.

Statistical analysis

Univariate comparisons were made between the three groups by using χ² test for categorical data and Fisher's exact test for binary proportions. Two-tailed values of P < 0.05 were considered statistically significant. Data analysis was performed using the SPSS software package (version 20.0, SPSS Inc., Chicago, IL).

Results and discussion

The final analysis included 90 patients. Totally 19 patients (21.1%) developed mild postoperative pain and 30 (33.3%) developed moderate pain. Most of the patients (41; 45.6%) developed severe postoperative pain.

The administered type of anaesthesia seemed to influence the postoperative pain intensity in such a way that patients who underwent general anaesthesia with endotracheal intubation were most likely to develop severe pain (62%) than either mild (19%) or moderate pain (19%). In addition, patients who underwent spinal anaesthesia were most likely to develop moderate pain (46.90%) than either severe (28.10%) or mild pain (25%) (Figure 1).

Figure 1. Postoperative pain intensity depending on the type of anaesthesia administered for total abdominal hysterectomy and bilateral salpingo-oophorectomy.

The χ² correlation coefficient between pain intensity and type of anaesthesia administered was 8.08, which was higher than the value in the Fisher Table (5.09) for two degrees of freedom. Therefore, there was a significant association between the type of anaesthesia used and the value of pain recorded in the NRS. From a statistical significance point of view, the P value was 0.018; therefore, there was a statistically significant difference between the two variables.

Regarding the environment of origin, 34% of the patients were from rural areas and the rest 65% – from urban areas. We compared the patients from urban areas with those coming from rural areas, according to the pain intensity felt, in order to find a statistically significant difference between the two variables.

Among the patients from rural areas, 22.58% experienced mild postoperative pain, 16.13% felt moderate pain and 61.29% felt severe pain. Among the cases from urban areas, 20.34% felt mild pain, 42.37% felt moderate pain and 37.29% experienced severe pain (Table 1). These results suggest that the patients from rural areas had a higher pain tolerance, compared to those from urban areas.

Table 1. Postoperative pain intensity after total abdominal hysterectomy and bilateral salpingo-oophorectomy according to the patients' place of origin (environment).

	Place of origin (environment)
Type of pain experienced	Rural areas (n = 31)	Urban areas (n = 59)
Mild pain	7 (22.58%)	12 (20.34%)
Moderate pain	5 (16.13%)	25 (42.37%)
Severe pain	19 (61.29%)	22 (37.29%)

The mean pain intensity on the NRS for patients coming from rural areas was 6.71 ± 2.58 and the mean pain intensity for patients coming from urban areas was 5.86 ± 2.43.

The obtained χ² for two degrees of freedom was 6.81, which was higher than χ² in Fisher's Table (5.09). The P value was 0.033; therefore, the correlation between the patients' environment and pain intensity on NRS was statistically significant.

The age of the patients ranged from 33 to 60 years, with an average of 46.81 years (with a standard deviation of 4.615). A number of patients (68; 75.6%) were under 50 years old and 22 patients (24.4%) were over 50 years old. Of the total number of 68 patients aged less than 50 years, 20.59% experienced mild pain, 30.88% experienced moderate pain and 48.53% felt severe pain. The percentage of patients over 50 years old who experienced mild pain was 22.73%, 22.72% experienced moderate pain and the remaining 54.55% (12 patients) felt severe pain.

By using Pearson correlation, we obtained P = 0.97. Therefore, there was no statistical significance between age and postoperative pain.

We also compared the three groups of patients (based on type of pain felt) by using the BMI, in order to determine if there were any correlations between certain weight category and the type of pain developed. There was no significant difference between the compared weight categories (P ≥ 0.05) (Table 2).

Table 2. Number of patients in each of the three groups (depending on type of pain felt) based on BMI.

Category	BMI range (kg/m^2)	Mild pain (n = 19)	Moderate pain (n = 25)	Severe pain (n = 46)	P
Normal weight	18.5–24.9	8 (42)	5 (20)	13 (28)	0.27
Overweight	25–29.9	5 (26)	9 (36)	22 (48)	0.24
Obese class I	30–34.9	2 (11)	9 (36)	7 (15)	0.05
Obese class II	35–39.9	4 (21)	1 (4)	4 (9)	0.16
Obese class III	>40	0 (0)	1 (4)	0 (0)	0.26

Note: Values are expressed as number of patients (per cent).

After hysterectomy, the pain may be of neuropathic or inflammatory origin.[7] Inflammatory pain is due to the stimulation of peripheral nociceptors by the inflammation mediators (cytokines, endothelin, bradykinin, prostaglandin E2, leukotrienes).[8,9] Neuropathic pain is induced by the injury of afferent sensory nerves lying across the surgical fields.[10]

Exteroceptive sensibility receptors are represented by free nerve endings. The axonal extensions of the neurons are present in the dorsal root ganglia of the spinal nerve (protoneuron). This is a pseudounipolar neuron, whose long dendrite reaches the receiver and its axon penetrates the spinal cord via the dorsal root, where it makes synaptic connections with deutoneuron of exteroceptive sensitivity. Its axon passes into the opposite side, where it forms lateral spinothalamic tract which goes to the thalamus.[11,12]

Considering the major route of the pain signal transmission to the higher centres, the tract is divided into:

• lateral spinothalamic (neospinothalamic): which arrives to the ventral posterior lateral thalamic nucleus (VPL) that carries the following pain characteristics: duration, intensity and location.[13] This tract conducts fast pain;

• medial spinothalamic (paleospinothalamic): which ends at the thalamic midline and intralaminar nuclei. It is responsible for mediating the autonomic reactions and the negative emotional perception of pain and slow pain transmission.[14]

The third neuron axons project to the cerebral cortex in the sensory areas of the parietal lobe, postcentral gyrus, areas 3, 1, 2.[15] When the nervous signal reaches the sensory cortex, the person becomes aware of pain.[16] International Association for the Study of Pain defines pain as ‘an unpleasant sensory and emotional experience, associated with actual or potential tissue damage, or described in terms of such damage’.[17]

There are several pain scales, such as the NRS, verbal rating scale or visual analogue scale, which are recommended for the assessment of pain intensity.[18] The NRS is applicable for one-dimensional assessment of pain intensity in most settings.[19]

Postoperative pain may be influenced by type of surgery, type of anaesthesia, preoperative care, age, emotional status or education of the patient. There are numerous studies that compare the efficiency of spinal anaesthesia versus general anaesthesia in terms of postoperative analgesia, but intrathecal opioids were used in all of them.[3–5]

The results from this study confirm those reported by Sprung et al. [20] in the Canadian Journal of Anaesthesia.[20] The study was conducted in the United States on 89 patients who received either general anaesthesia or spinal anaesthesia for vaginal hysterectomy and were observed for 24 h after surgery. The same patients were called two weeks after discharge. It was observed that the patients with regional anaesthesia, needed postoperatively a smaller dose of morphine than those who received a general anaesthesia (P < 0.001). Two weeks after discharge, 69% of the patients with spinal anaesthesia and 48% of those with general anaesthesia, said that they did not have pain (P = 0.04).[20]

Two years later, Tyritzis et al. [21], in their article in ISRN Urology, analysed the effect of the chosen anaesthesia type on the intensity of postoperative pain. The study group consisted of 94 patients who had undergone resections of bladder tumour and 47 patients who required surgical treatment of prostate adenoma. It was observed that, statistically (P = 0.027), patients who received general anaesthesia experienced higher intensity of pain than those who administered spinal anaesthesia.[21]

In our research, 45.6% of the patients felt severe pain, 33.3% of them felt moderate pain and only 21.1% felt mild pain. We observed that the average intensity of pain according to the NRS was 6.16 ± 2.51 and the mean value of severe pain was 8.26 ± 1.10 during the first 24 h after the procedure. We found that more patients developed severe pain after general anaesthesia, compared to those who underwent spinal anaesthesia. Also, we should mention that none of the patients received intraspinal opioids.

A study conducted in 2011 which included 213 patients, kept trace of the postoperative pain for a period of 4 h.[22] The patients living in urban areas reported lack of pain control, as opposed to those from rural areas: 68% compared to 34%, respectively (P = 0.028).[22] This finding has been observed in another study as well.[23] Therefore, we suggest that this connection may have cultural components and it should be further detailed.[23]

Researches in the field have emphasised the fact that the environment actively influences the physical and psychic health of women, irrespective of their age, ethnicity or religion. Thus, it has been proven that pain tolerance is higher for women who live in a rural environment than for those who live in an urban environment, as more than half of the former are intensely exposed to physical effort during their daily activities. Women in urban areas face an increased level of stress, whose main factor is the excessive psychic involvement in social and professional life, which, in time, affects the state of the organism and determines lower pain tolerance. This aspect has been noted during surgical procedures and postoperative care.

In this study, a significant correlation was observed between the patients' environment (rural/urban) and the developed type of postoperative pain (P = 0.033).

Other studies, such as the one of Gagliese and Katz,[24] show that older patients require less opioid than young people. We did not obtain a significant correlation between the age groups (less than 50 years old versus 50 and above) and postoperative pain.

A study from 1997, which included 2965 patients, concluded that there is a statistical correlation between BMI and postoperative pain.[25] The obtained results showed that obese patients developed severe pain more often.[25] A recent study, from 2012, highlights no statistically significant differences when comparing the mean pain scores by BMI.[26] We also compared BMI with the type of pain developed, but we could not identify a statistical correlation between the two.

Conclusions

The patients who administered spinal anaesthesia with bupivacaine 5% without intrathecal administration of opioids experienced severe postoperative pain less frequently than the patients who underwent total hysterectomy with bilateral salpingo-oophorectomy under general anaesthesia. The results from our comparative analysis showed that a higher percentage of patients from rural areas had lower score of postoperative pain intensity on the NRS than the patients from urban areas. However, this study did not reveal any statistically significant differences when comparing the mean pain scores regarding age or BMI.

Dısclosure statement

No potential conflict of interest was reported by the authors.