Laser Cone Research Articles

Endocervical cell retrieval following excisional treatment of CIN

The purpose of our study was to compare laser cone excision with large loop excision of the transformation zone with particular respect to the retrieval of endocervical cells on follow-up cervical cytology. Retrospective analysis of case records of 368 women who had large loop excision of the transformation zone and 188 women who had laser cone excision for suspected CIN changes at Middlemore Hospital, Auckland. The retrieval of endocervical cells on cervical cytology following large loop excision was 94.7% and 85.2% following laser cone excision. Laser cone excision was associated with a higher chance of normal follow-up cervical cytology. The retrieval of endocervical cells was satisfactory following both large loop excision and laser cone excision. Laser cone excision is recommended with large or more severe lesions.

Local therapy and adjuvant interferon therapy in genital papilloma virus infections

Is it possible to reduce the recurrence rates of HPV-positive genital tract lesions by systemic interferon alfa-2a in addition to local therapy? Thirty-three of 63 patients with first manifestation of papillomavirus infection or monolocal manifestation were treated by local therapy. The other 30 patients with recurrent or multiorgan infections received 3 courses with 12 x 10(6) IU interferon alfa-2a subcutaneously. For the remaining 47 patients (16 were lost to follow-up) we found a significantly lower recurrence rate of 21% (5 of 24) in the group of interferon-treated patients compared to 52% (12 of 23) of patients treated without interferon. The systemic treatment of HPV-positive genital tract lesions with interferon alfa-2a in addition to CO2 laser surgery or cone biopsy seems to reduce the recurrence rates of HPV-positive lesions.

A Randomized Prospective Study Comparing Three Techniques of Conization: Cold Knife, Laser, and LEEP

Three different techniques of cervical excision, cold knife conization, laser conization, and loop electrosurgical excisional procedure (LEEP) were prospectively compared with respect to treatment reliability, effectiveness, and safety. One hundred ten women with CIN1-2 and the sqnamnocolumnar junction not seen or CIN3 at the original diagnosis were randomized to treatment with cold knife conization (n = 37), laser conization (n = 37), or LEEP (n = 36). All three treatments were performed with local anesthesia on an outpatient basis. The mean age, histologic features (original and histology of the conization), endocervical involvement, and ectocervical extension were similar in the three groups. Blood loss and operating time were less (P < 0.01) in the LEEP group (5.4 cc of mean blood loss and 5.4 min mean duration time) than in the two other groups (16.2 cc and 14.0 min for cold knife conization, 21.5 cc and 15.6 min for laser conization). Volumes of the cones were evaluated: LEEP cones and laser cones were smaller than the cold knife cones (P < 0.001). During the pathological review of the conization, the major problem was difficulty in evaluating the lesion and its margins due to the coagulation induced by the laser or the LEEP. This alteration was present in 53% of the LEEP conization specimens and in 51% of the laser conization specimens. In the majority of the cases the coagulation was mild, but in one case (LEEP group) and in two cases (laser group) the conization was totally altered by the coagulation, and in 31% of all the LEEP conizations and 38% of all the laser conizations, evaluation of the entire margin was not possible due to coagulation of the tissue. During postoperative follow-up, the number of complications was the same in the three groups (two episodes of post-operative bleeding in each of the three groups). Two months after the treatment the cervix was evaluated: the os was diminished in the cold knife group compared to the two other groups and as a result, the squamnocolumnar junction was not seen in entirety in 50% of cold knife cases, in 19% of LEEP cases, and in 20% of laser cases. These results suggest that in our hands: (1) laser conization is relatively costly and time consuming and alters the tissues significantly, and (2) the choice between cold knife and LEEP is more difficult—cold knife gives a sample adequate for histological evaluation (including evaluation of the margins), while the LEEP procedure is technically easier and less time consuming but sometimes induces electrocautery artifact so that evaluation of the margins is not possible.

Conservative Therapy for Microinvasive Carcinoma of the Uterine Cervix

The purpose of this study was to evaluate conservative therapy for microinvasive carcinoma (MIC) of the cervix. Large contact Nd-YAG laser conization (laser cone) with contact vaporization using contact probes was performed on 90 cases of MIC and 21 cases of early invasive carcinoma (early IC), with long-term postoperative follow-up for patients at Osaka Medical College, Osaka, Japan. The cure rates of MIC and early IC were 96.7 and 80.9%, respectively. The rates of incomplete excision and true residuation in cases with MIC were 17.8 and 10.0% and those in cases with early IC were 76.2 and 19.0%. Therefore, the spontaneous cure rate following incomplete excision of MIC and early IC was 43.7 and 75.0%. Hysterectomy was performed, for various indications, after cone in 5 patients (5.6%) with MIC, none of the patients with IC of less than 3 mm, 2 (22.2%) of the patients with IC of 3.1 to 5 mm, and 7 patients (87.5%) whose IC was 5.1 mm or more in depth. Combining the data from our department and those in the literature collected an incidence of lymph node metastasis of 0.15% for MIC and of 1.13% for IC of less than 5 mm. In conclusion, conservative therapy is indicated for MIC, and the contact laser cone with contact vaporization is considered to be an excellent therapeutic conservative method.

Loop electrosurgical excision procedures for cervical dysplasia: Experience in a community hospital

The study was undertaken to evaluate the use of the loop electrosurgical excision procedure as an outpatient hospital or surgicenter procedure. The records of 358 patients treated for cervical intraepithelial neoplasia at a large community hospital over a 1-year period were reviewed. The specimens obtained by loop electrosurgical excision procedure and laser cone excision were comparable in size but smaller than those by means of cold-knife conization. Seventy-two percent of loop electrosurgical excision procedure specimens consisted of two to eight tissue fragments (mean 3.4). In addition, 48% of the loop electrosurgical excision procedure specimens and 38% of laser cones had moderate or severe thermal artifacts. Fragmentation and cautery damage precluded orientation of tissue and evaluation of margins in 19% of the cases. The advent of the loop electrosurgical excision procedure has shifted the management of cervical intraepithelial neoplasia from the office to the outpatient surgery centers. This negates and, in fact, reverses the advantage of loop electrosurgical excision procedure over other methods in regard to cost and convenience through evaluating and treating a patient with cervical intraepithelial neoplasia in one office visit. Loop electrosurgical excision procedures provide specimens that are inferior compared with cold-knife cones; therefore the role of loop electrosurgical excision procedure for the management of cervical intraepithelial neoplasia outside the office appears limited.

The Case for Conservative Management of "Incomplete Excision" of CIN after Laser Conization

Three hundred thirteen laser cone biopsies were performed for cervical intraepithelial neoplasia (CIN) over a 4-year period. The mean age of the patients was 39.9 years and average cytology follow-up was just under 3 years. Six patients defaulted colposcopic review and were excluded from analysis. Of the 75 cases with CIN extending to the endocervical resection margin, 9 (12%) were found to have residual disease. Only 2 (3.6%) of 56 cases with CIN extending to the ectocervical margin had residual GIN detected. In the 176 cases in which the CIN lesion was excised completely there have been no cases of residual CIN. The overall detection of residual disease was 3.6%. Further surgery in those cases with CIN extending to the resection margin is excessive. These patients should be managed conservatively with regular cytological follow-up.

Lack of effect of topical iodostearic acid on cervical intraepithelial neoplasia II–III

Stearic and iodostearic acid inhibit growth of a cervical carcinoma cell line in vitro. This study was performed to determine if iodostearic acid would induce regression of cervical intraepithelial neoplasia (CIN). Women with histologically-proven CIN II or III were randomised into two groups. Those in the first group were given pessaries composed of iodostearic acid in polyethylene glycol (PEG) base. Women in the second group were given pessaries containing only the PEG base. One pessary was inserted into the vagina nightly for 30 nights, and each woman then had the CIN lesion removed by CO 2 laser cone excision. There was no difference in the histology of the cone biopsies between the groups, demonstrating that this regime of iodostearic acid has no useful role in the treatment of CIN II–III.

The histologic reliability of laser cone biopsy of the cervix

Laser conization of the cervix has been advocated as the technique of choice for the treatment of cervical intraepithelial neoplasia (CIN) in preference to ablative techniques, because it provides a specimen for histologic diagnosis while retaining the advantages of an outpatient procedure with minimal short- and long-term morbidity. To determine whether specimens so obtained are adequate for reliable histologic diagnosis, we reviewed 77 laser conizations performed for lesions confirmed to contain CIN in a colposcopically directed biopsy and satisfying the criteria for local ablation and scored the cones for the presence of epithelial denudation and laser coagulation artifact that interfered with the diagnosis of CIN or the assessment of the margins of excision. Thirty specimens (39%) were negative for CIN. Twenty-eight (36%) showed extensive epithelial denudation, ten (13%) contained coagulation artifact that made recognition of CIN extremely difficult or impossible, and in 11 (14%), assessment of margins was extremely difficult or impossible because of laser coagulation artifact. We conclude that these difficulties with the histologic interpretation of laser cone specimens make it an unsuitable excisional technique when reliable histologic diagnosis of cervical lesions is required.

Clinical evaluation of contact Nd.YAG laser conization for cervical intraepithelial neoplasia of the uterus.

Contact Nd.YAG laser conization (laser cone) was performed in 500 patients with preoperatively diagnosed cervical intraepithelial neoplasia (CIN) since September 1983. The patients treated were followed for 12 to 96 months (39.2 months on average). Average operation time was 11.4 minutes. A cure with laser cone (single treatment) was achieved in 98.6%, including cases with microinvasive and invasive carcinoma, post-operatively. There were only 7 (1.4%) true residual cases of 47 cases (9.4% of total cases) with incomplete excision. High spontaneous cure rates (85.1%) in cases with incomplete excision are considered to be a characteristic of laser cone treatment. The contact laser cone method also got good specimens for histologic examinations. They gave a large amount of information for our follow-up. The results indicate that contact Nd.YAG laser conization for CIN is an excellent conservative therapy from the point of cure rate, safety, indication, operation time and cone specimen, even compared with CO2 laser conization.

Ten year follow-up study of women presenting to a genitourinary medicine clinic with anogenital warts.

One hundred heterosexual women presenting at our clinic in 1979 with anogenital warts, were reviewed 10 years later. Median duration of warts following initial clinic attendance was 2 months (range 0-120 months). In 1979 cervical PAP smear results were available for 76 patients; cervical intraepithelial neoplasia (CIN) was seen in 15/76 (19.7%) women; 3 (4%) women had low grade CIN, 12 (15.7%) women had high grade CIN. Nineteen women had had treatment for CIN between 1979 and 1989, 7 laser ablation, 9 cone biopsy, 2 laser ablation and cone biopsy, and one woman laser ablation, cauterization and cone biopsy. At 10-year follow-up in 1989 4/100 women had anogenital warts, 12/100 women had cytological evidence of CIN (7 low grade, 5 high grade), and 37/100 women had CIN detected on colposcopic biopsy (31 low grade, 6 high grade). No women developed invasive cervical carcinoma during the study period. CIN lesions, detected in 1979, regressed without any treatment in 2 women. Colposcopic biopsy was 3.1 times more sensitive than single cervical PAP smear at detecting CIN (4.4 times as sensitive in detecting low grade CIN; 1.2 times as sensitive in detecting high grade CIN). In 1989 CIN was detected in 7/19 (36.8%) of women who had undergone cervical treatment between 1979 and 1989, and in 35/81 (43.2%) of women having no cervical treatment within this period (chi squared P greater than 0.5). These findings suggest that cervical laser ablative therapy and cone biopsy do not in the long term influence the natural history of cervical human papilloma virus-associated disease (CIN) in women with anogenital warts.(ABSTRACT TRUNCATED AT 250 WORDS)

Obstetric outcome after cervical surgery for intra-epithelial neoplasia

SummaryIn a four year prospective case-controlled study, patients undergoing either carbon dioxide laser ablation or large loop excision of the transformation zone for cervical intra-epithelial neoplasia were studied during subsequent pregnancy and delivery. A total of 143 patients treated conceived and concluded an intra-uterine pregnancy within the study period. One hundred and seventeen were treated with carbon dioxide laser ablation, 3 were treated by laser cone biopsy and 23 underwent large loop excision. There was no difference in pregnancy outcome in those women who had undergone cervical surgery compared to matched controls in terms of spontaneous abortion, progress oflabour, mode of delivery or complications. These methods of treating cervical intra-epithelial neoplasia have no deleterious effect on pregnancy outcome.

Reliability of colposcopy and directed punch biopsy

A group of 118 women underwent laser cone biopsy. Data were collected routinely on proforma case notes and entered into a computerized database. The histology of the cone biopsies was compared with that of previous, colposcopically directed punch biopsies, with the cytology of smears taken in the clinic and with the colposcopic diagnosis. The punch biopsy had a 54% false negative rate and neither of the two microinvasive carcinomas biopsied in this way were detected by the biopsy. Ten of 24 women with negative punch biopsies had CIN III in the cone. When the punch biopsy showed CIN II or worse, the cone biopsy confirmed the presence of CIN in 86%. There was some evidence of false negative cone biopsies. The data suggest that management should not be based solely upon the punch biopsy result but should include consideration of the cytology and colposcopy findings. Excisional methods of treatment are more likely to reveal early invasion and adenocarcinoma-in-situ.

Is it time for a reconsideration of the criteria for cone biopsy?

Between August 1985 and November 1988, 475 laser cone biopsies were performed at the Regional Gynaecological Oncology Unit in Gateshead. Of these, 332 were performed for abnormal cervical cytology and unsatisfactory colposcopy. The negative cone rate in this group was 34%. In those with cytological abnormalities up to and including mild dyskaryosis the figure was 64% and there were no cases of invasive disease. In this group the authors have reconsidered the criteria for cone biopsy and suggested biopsy of the visible ectocervical lesion combined with endocervical curettage or brushing. Those with negative histology or cytological abnormalities less than moderate dyskaryosis should be managed conservatively.

Cytological status and lesion size: a further dimension in cervical intraepithelial neoplasia.

Quantitative histological study of 84 laser cone biopsies showed a highly significant correlation between the grade of a cervical smear and the size of the lesion for all grades of cervical intraepithelial neoplasia (CIN) (CIN I P = 0.004; CIN II P = 0.0001; CIN III P = 0.003; total CIN P less than 0.0001); 10 of 34 (29%) of women with CIN III and mild dyskaryosis or less had significantly smaller lesions than 23 of 36 (63%) of women with CIN III and moderate or severe dyskaryosis. Repeat cytology identified as severe dyskaryosis all those with large CIN III lesions. Lesion size has been neglected in studies of the natural history of CIN and in the assessment of cytological screening, but offers an explanation for the apparent discrepancies between cytological, colposcopic and histological assessment of progression of CIN.

Conical targets for implosion studies with a CO2 laser

The design, fabrication, and testing of conical laser fusion targets is described. These are DT-filled conical holes in lead, 190 μm deep and covered with a 132-μm-diam plastic cap. The results of two-dimensional simulations of the cones are displayed. Experimentally, up to 2.8×105 neutrons have been obtained from the exploding pusher implosion of such a target under single-beam CO2 illumination of the cap at 0.13 TW.

Electron density distribution in a conical laser plasma tube

The electron density distribution is determined for a low-pressure gas in a conical plasma tube. The distribution is found to vary in the radial direction as a spherical Bessel function and in the ϑ direction as a Legendre polynomial, the order of which is proportional to L/a.

Use of the C-5 Laser Cone by School Age Children

The use of electronic travel devices with blind school age children is a fairly recent development. The use of the Laser Cane with four blind students attending public school is discussed with emphasis on modifications in technique needed to integrate the cane's use into each student's travel system.

Focusing of an Intense Relativistic Electron Beam by a Hollow Conical Laser Beam

Abstract Estimates suggest that the nonlinear transverse radiation pressure produced within a plasma by a convergent annular high power laser beam may lead to the focusing of an intense relativistic electron down to a radius of ~10-4 cm. The transverse radiation pressure results from the dielectric property of a plasma in conjunction with the phenomena of the self-focusing of intense laser light. The tightly focused electron beams would make possible the release of thermonuclear energy by micro-explosions.

Spectral responses of laser cone calorimeters

For a polished nickel plated cone of angle 15 degrees , calculation suggests an optical absorption (response) which, normalized to unity at wavelength 0.4 mu m, falls to 0.99 at 0.7 mu m, 0.95 at 1.5 mu m, 0.90 at 1.9 mu m, and 0.85 at 2.3 mu m. Experimental comparison of the readings of such a cone calorimeter with those of a black detector, using different broad band radiations, is found to confirm this spectral response quite closely.

A radiation thermopile for cw and laser pulse measurement

A radiation thermopile is described with a flat circular black target 1 cm in diameter over which cw responsivity is almost uniform. It is intended for measuring the energy of radiation pulses as well as cw irradiance and beam power. Rise time for a very short pulse is about 1/4s and cooling time constant 8 s. Typical CW responsivity is 250 mV W-1, and peak-reading pulse responsivity 32 mV J-1, uniform over wavelengths from 0.4 mu m to beyond 10 mu m. Power and energy signal characteristics are closely linear. Design calibration and methods of use, for example in calibrating laser cone calorimeters, are described. With laser pulses, use is limited to about 0.1 J, 1 ms free-running. An alternative model, but with uniform spectral response extending only to 1.2 mu m in the infrared, will withstand free-running pulses up to about 1.5 J, and Q-switched pulses up to about 20 mJ.